[Imp]

Never reallly think about it buy for the type of force I fancy & so many variables like visibility terrain & the APC truck.
Trucks are fast on roads ok offroad if have 4WD but have limited use ferry to front & run in back areas.
APCs Wheeled often even faster tracked to sometimes good in heavy going. This allows you to get spotters out front ATGMs in position to cover your tanks advance.
They can be used further forward or even with care in the thick of it as not vulnerable to small arms.
If have smoke dischargers can be a life saver or alllow unloading hidden where a truck can't.
As discussed can Z fire a company firing at tree line makes a diffrence.
Can support your troops adding to survivability.
If have decent fire control & cannon or fast with AA ability great helo killers.
Less chance of sticking in rough terrain.
Safer option for exploiting a breakthrough.
Probably more thats just what comes to mind APCs are flexible trucks are not.

Troopie you could have problems playing the bad boys in current times then from the patch looks like they have gone for IFVs or urban vehicles your basic APC has had its day.