Firing Ports

[CStock88]

I know this might sound like a really dumb question, but as someone whose primary military knowledge is the knowledge that he doesn't really know anything, I felt that it'd be good to ask to get some kind of clarification (if only to assuage my own curious mind!)...

...Firing ports on IFVs. I understand that they're there to allow the infantry being carried by the IFV to add their firepower to their vehicle without dismounting, but... how effective are they, really? Also, what would be the typical method for using them?

To be honest, ten guys blazing away through a small hole while their IFV rolls across anything rougher than, say, gently sloping hills, strikes me as kind of a... well, a silly prospect, really. Of course, I don't really know anything about it, so...

For some reason, I've always had the image in my mind that it was usually a better idea, if you're going to engage the enemy, to roll up to the engagement zone, pop smoke, dismount, and then use the infantry and the IFVs in concert to achieve the destruction / pacification of the target, whether through using the IFVs as a base of fire, or whatever method.

This particular train of thought struck me today while, in my free time on my day off, I was cooking up my next campaign for my friends and I, and I read about how the BMP-1 was such a major improvement. Of course, I also read that the M2 Bradley series has gotten rid of their firing ports...? Is this a reflection on the idea that firing ports really don't work that well?

Any clarification on this particular aspect of mechanized infantry warfare would be really appreciated!