Personally, mortar squads are hugely underrated. I’ve score 20+ kills many times with a solid barrage. It all depends on where you expect the enemy to be. I wouldn’t call them underwhelming at all.
They’re a very situational, but effective squad. Not to everyone’s taste, but I don’t think they need a buff or a nerf. They just need practice.
I don’t really think we need heavy mortar in this game since they will be OP in such a small map.
Wall mortars definitely need to be revisited especially in Japan’s case, I wouldn’t say that they’re slept on due to being underwhelming. I say this because I’ve single-handedly irritated an entire enemy team to the point to where 10 out of 10 people were trying to kill me. Matches like that usually end in a win because I harassed the enemy team enough with mortars usually leading to my mortarman by themselves with just mortar strikes getting 40+ kills at a minimum.
I honestly don’t think so. Most of the time they are just gamble, a slightly influenced by the player’s knowledge of the game.
In most cases, you’d be far more efficient with more or less any other class in that timeframe.
If only for the reason that during the time you are using the mortar, the actual bodies of your squad are simply missing on objective or any other shoot out in which your teammates can get overwhelmed.
And when you put this in the context that F2P players can only have 3 infantry squads. It’s really no wonder so many people don’t use that squad.
More stuff = more good
But like others have already said, +100mm mortars could be too heavy for a soldier to carry. Also their model could simply not work well with soldier models (some are as tall as a human).
Also my two cents on mortars in general:
I’d like mortar aiming to be a bit simpler, similar to BF series but without enemy markers (and 3rd person view). We can already do this basically but it requires unnecesarry extra steps so some streamlining would be welcomed.
Add CREW to mortars!
I want to see 2 soldiers operating a mortar for increased rate of fire (and maybe extra reserve ammo) similar to AT guns. One aiming and the other one loading. This would be super cool.
A bit unrelated but give grenade launchers option for indirect (mortar) fire. This would effectively allow all squads to have a very weak mortar for some extra utility while the powerfull stuff is still locked to mortar squad.
It’s pure fantasy with the current state of AI and AI orders (or lack of them) but…
I’d like to have option to use binoculars as a forward observer while my AI shoots mortars at designated positions. I think it could be very interesting gameplay option.
It’s all quite unrelated to the main post but since the topic is called “Mortar revamp” I don’t feel any guilt for spaming out my ideas 
Bigger maps, simple
Lol simple?
Where is it then?
I don’t really see such thing that is that simple after playing this game for several years.
Or maybe just introduce howtizer to mortar men squads?
Imo howitzer is a bad choice as it’s simply too big.
I’d rather give them mobile infantry support guns for direct fire with HE shells. Suits the squad and gives them a bit more active role than firing even bigger HE from even further away.
They are only good on very few highly exposed areas where you have a lot of troops trying to defend it. Pacific is the best for some mortar plays but other campaign have a lot of points inside buildings or bunkers so it will make your mortar shells completely useless.
You can’t pick the front and map you want to play so if game rngs you into some Berlin/Moscow map you will struggle with a worthless squad.
could work,yes
not that big + new idea for new soldier class, and
howtizer = infantry support gun
It has like +5km range for indirect fire. That’s why I say it’s too “big”.
And if you want to get rid of indirect fire, better use something actually designed for direct fire. Like infantry support guns.
I don’t think adding “boat with wheels to a desert” for the sake of artificial variety is a good idea.
Howitzers support infantry but they aren’t infantry support guns, that’s a separate category of guns.
Mortar revamp for me is make my bot fire the mortar while I order them were fire with the binoculars
Well, the DEV’s need to give more then one mortar squad per faction as I am far to lazy to change my one mortar squad from level 3 to level 5 and back again, so, I just use them in level 5.
they are excellent on open cap maps (specially if you are attacker that needs to clear cap), but they suck on closed cap. also having spotter marking things increases mortar effectiveness by a lot.
overall they are very situational as solo player and arent really good choice for first 3-4 infantry squad slots.
since they are very rarely played, the clearly need improvements.
your caliber system makes sense and dont worry, they wont be OP, as mortars themselves are inferior to other weapon types (smgs will get much more accomplished), so making them superficially OP is required to bring them on par with other weapons.
similar concept as low BR planes being able to carry heavy bombs, as planes themselves have quite the low impact relative to other squads.
the super heavy mortars around 100mm need to be structures. a) to give the mortar squad its own structure and b) due to realism, as not even 2 humans together could carry such a thing into battle.
the last improvement to make the squad work is the ability to order your second engineer to fire together with you.
DF can release these improvements together with some premium squads using things like nebelwerfer, which mostly function like a mix of mortars and artillery. cant wait to fling 20kg molotovs/gasgrenades across the battlefield on bumrushing hordes.
there was a time … 
The issue here is the same issue Aircraft and tanks have but far worse it requires your team to know where the V key is and the mortar player to have something between his or her ears the mortars is issue is the skill ceiling is far too high.
The only logical answer is that Heavy Mortars should be the Mortar squad’s unique building. It literally goes without saying.
Infantry Support Guns should be added as a universal Engineer building