It's useless not only at daytime, but also inside many bases with lost of light sources and shiny surfaces. And, it's definitely just BROKEN when compared to any other scope with just maxed out brightness slider. We don't need 30certs brightness setting, that in most cases makes the screen competely white. We need true IR scope, like on veh weapons. Or rebalance the contrast.
Yes, it's good. But smoke is not infinite (unless playing Engi) and not always smoke is good for a situation.
Smoke is good in any situation where they can't see through it, but you can. It's why my LA always carries smoke grenades. I toss a couple in and waltz in like Rambo. Bodies pile up, and then I have to get out because I start tripping over them.... Unless, of course, someone else has the right optics and ruins my party.
Problem being many players play with setting that make smoke a pathetically small area and it doesnt last very long either.
Don't forget about Q-spam. Everyone doing this when they see smoke. But for LA it's still awesome. I once killed few 80+ HA in smoked room, sitting ontop of some closet-thingy. HM... just realized... SUGGESTION - disable spotting through smoke!