Wouldn't giving all infantry the exact same anti-building weapon (timed C4) provide the opposite effect to the intention of "make them more different" and "make them less boring"?
This engine really is not designed for weapon bloat. It's hard enough to use the Engineer right now, they have five weapons and making sure that you can scroll to the exact right one when needed (for example, using clearing charges against mines instead of accidentally throwing your anti-building C4) is awkward. This also why Tanya/Volkov, who used to have binoculars, no longer have them - because it's painful to accidentally switch to binoculars when you want to switch to your C4 as Tanya or switch to your alternate anti-unit option as Volkov. Why should we make this an even bigger issue than it already is?
On top of that, one of the things I see new players have trouble with is characters that have multiple weapons. It is very common to see newbies keep using Volkov's AT cannon against infantry, or keep using the LAW/RPG-7 against aircraft when the Redeye/Strela exist and can clearly be seen holstered on the soldier's back.
In the past I've considered giving most infantry a LAW/RPG with 1 ammo and nerfing the power of bullets vs tanks to compensate, for the purpose of making infantry against tanks look less silly and giving further incentive for the Supply Truck - but the weapon bloat, newbie-unfriendliness, and homogenization issues just complicate matters. It's still up for debate though; it's probably the only "add more weapons" thing that I'll ever consider, but another problem is that it would shake up the balance of a gameplay area that, as far as I can tell, is in a pretty good spot right now and doesn't need much change.
Oh, and if we're supposed to go whole hog giving every infantry a "full loadout" with like 2 or 3 unique weapons each, then we run into the issue of where do we get the weapon models? Most of the old team is long gone and everyone around here with modeling experience is too busy working on stuff for other projects and stuff that's more important than "extra weapons for units that already have a weapon and work just fine with what they have".