I'd say crits are important to keep the game somewhat fluid.
When both team are solidly entrenched, with good medic support and overheal, the random crits are one of the only way to actually kill someone and maybe break the stalemate.
Yeah and thats where tactics come into play. You know, people actually having to work together, communicate and set up a decent attack?
Oh yeah it's great when it happens.
But this is a public server with random people joining and quitting all the time, playing whatever class they want.
Sometimes it's really great, really nice team, and other times it's difficult to get proper engy and medic support. Game can become quite frustrating at that point if you need
other people to have fun.
General comment, not at all against you, but every gameplay imbalance can be explained away with the "moar teamplay" card. Requiring too much teamplay from pub servers doesn't work really well in my experience.
When I play TF2 I usually prefer fluid games to stalemates, so I prefer gameplay balance tweaked to limit formation of deadlocks. Like 2 snipers slots, 4 demo max, and now maybe limiting number of engies (cause wall of wrangled sentry is >> uber).
Just my point of view.