We've all snuck up behind a tank, only to have the driver pop out instantaniously and spray us down before we can even react...
We've all been driving a tank, and had a Clowncar blow by behind us, had the driver jump out, drop a satchel, and get back in before we can get the turret around...
Both of these situations are "gamey" and it's been suggested that a delay be added when entering and exiting a vehicle. While in an ideal world, we'd have animation showing your avatar opening the hatch, climbing out, and jumping down... I realize this is a royal pain to code and model within the limitations set by the UT engine.
What I'd like to suggest is a simple compromise that involves NO additional art resources and which I would imagine shouldn't be too hard to code:
Only allow exit from a vehicle when the hatch is open. If you're in the gunsite or zoomed in driver view, you have to mousewheel scroll back to open hatches before you can hit use to jump out.
This causes a (small) delay while the already existing hatch open animation runs. It also has the affect of giving warning to people outside that you're exiting the tank (ie they see the hatch open).
This adds the desirable effect of making tanks more dependent on supporting infantry, without swinging the pendulum as far as a full delay and animation would. (which in my opinion would neccesitate limiting the number of satchels and panzerfausts that can be carried to more realistic levels)