(By 'squad vehicles', I simply mean vehicles tailored to situate a 4-6 guys)
This is a suggestion of new content for the future Expansion.
As of the current state of Arma 3 Vanilla, you have 3 main choices regarding squad vehicles. The Ifrit, the Strider, and the Hunter (and to a lesser extent, perhaps the armed off-road, although it does not fit the case). These vehicles are fine and all, but they are all MRAPs, and consequently are very well armored.Considering these are also the go-to de facto squad vehicle as of now, they are also in ample supply.
These two do not mix very well in the multiplayer environment, and it is not uncommon to witness a game of "wack-a-mole" as drivers of MRAPs will simply use their small arms resistant vehicles as lawn mowers against nearby foes until their tires have been destroyed or they are otherwise disabled.
In the more organized, private communities, MRAPs are not very common (in my experience). The small arms resistant vehicles (and to a degree, mine resistant) make for uninteresting game play. Some communities, such as ShacTac, can hardly ever be seen utilizing them because of their thermal and armored qualities.
What I'm trying to say is that there should be some form of lightly armored or unarmored military vehicle for each faction. Even though MRAPs are vulnerable to small arms fire in their glass ports, they are still reasonable difficult to engage, especially at distance. Being in an MRAP makes you feel relatively safe, and you probably wouldn't be extremely worried if you can under small arms fire. However, in a lightly armored variant, you would almost certainly seek cover or double back. These vehicles could be done in a style similar to Humvees or UAZs in Arma 2, using minimal or no small arms armor, and have simple variants based around weaponry.
You could now see the return of the expendable squad vehicles, and still have MRAPs sprinkled in-between for special units. It would make for some more interesting game-play opportunities and I'm absolutely certain it would be well appreciated by the community.
At the very least, I would ask that some form of exposed MRAP is made; one where the gunner is out in the open using a mounted weapon with little protection and no thermal vision. This would use a lot less dev time but still deliver essentially the same effect, making combined arms game-play more interesting.