No one uses them because they're a high level unlock and stick out more than a bb when using engineer.
I use Engineer on almost every setup. Unfortunately, I'm color blind and whenever the item is overlapped by green/brown in the game, I can't see it
I wish the 'color blind' setting in the options menu addressed this. But I seem to really only have a consistent problem with shock charges. 90% of the time I won't see them with engineer. Claymores do stand out a lot, more so than betties. But betties are usually pretty easy to see.
they can start by not having three items in a bouncing betty, C4, and claymore that are very similar
i don't see a benefit of going with normal grenades or semtex compared to the C4 other than being able to chuck them way way further, the C4's blast radius is way bigger than those anyway
I think they are all pretty unique, I use them all but semtex.
Betty and claymores are both the only ones that are automatically detonated remotely. A lot of people like not having to worry about when to use the equipment. I use claymores a good deal if the other team isn't running Engineer. I don't use betties, but since you can toss them I see their purpose where claymores wouldn't work. I've been playing non-stop since release and IMO betties are the most used lethal. Lots of people do like their automatic nature.
Normal grenades are extremely good IMO. If I'm not using C4, odds are I'm using normal grenades. Their distance is huge and you can prime them. If I'm playing something like Domination and providing a defensive role, high odds I'm using normal grenades. You can provide suppresive fire from a great distance, while still being able to throw normal grenades. C4 and betties don't even go nearly as far.
C4 is what I use on my rushing classes. I mostly use it to clear sniper nests while running by it. On maps like meltdown where there are always people camping the 2nd stories, you can run by and throw a C4 up there, likely killing 1-2 campers.
Semtex I have no use for. Don't see what advantage over normal grenades it offers. They're fun to use against people using shields. You just stick it to their shield and walk away. Beyond that, they don't do much for me.