Well the thing is it depends very much on how and what you play. For example, I would never use a suppressor if I was defending on Rush, in fact I probably wouldn't bother if I was attacking either, but I never play Rush. When I'm with my usual squad playing CQ, we always go to the least populated enemy-held flag, but of course you can only see your friendlies on the map so the 'least populated flag' isn't necessarily the genuinely least populated, there could be a squad or two hanging around or spawning there. So we like to choose a low-traffic, high-cover route to these objectives and then start capping; the element of surprise in this tactic is more important than anything else. We also have good medics, in fact recently we've had three medics and one engineer (which we switch up depending on the armour dominance of the server) so if we lose out in a gunfight to unsuppressed weapons it's no big deal. Then when we cap and secure (i.e. kill everyone near to) that flag we leave immediately for the next one.
Although I rarely Recon now, being a hidden, aggressive Recon (i.e. non-glare scope and suppressor on a semi-auto rifle) had huge benefits; you could get into a cap zone and snipe approaching defenders at relatively close range without as much fear of being knifed in the back. Even if you didn't get any kills they'd arrive suppressed and injured so the rest of the squad could finish them off (or do most of the work, but not all of it). A suppressed LMG on a bipod worked in this role too.
But yeah, if you play to the strengths of the weapon in the way you have it set up it's all fine. Like, if I have a semi-auto rifle with a holo and suppressor (as I most often do with the Mk11 Mod 0), the fact that I'm using a close range optic means the slower bullet velocity and exaggerated drop aren't a problem any more, and at the same time the fact that I have a fire rate disadvantage means I want to stay hidden for as long as possible so I stand a chance of getting a shot off before I'm even noticed.
So you're right, not all situations suit suppressors, but you normally have a certain amount of control over the situations you find yourself in if you're aware of what's going on. And even if a game goes completely against how you intended, I'd prefer to have the suppressor and not need it rather than need it and not have it.
Edit: Wow, I'm on a wall of text streak lately...