Powers that negate concealment, invisbility- Worth it?

[Stalker0]

One thing I've noted while reading arcane power is that there seem to a LOT of powers that negate invisibility and/or concealment.

Now I like using a lot of terrain my games, but so far concealment doesn't come up that often, and invisibility is very very rare. I personally feel currently that these powers are a waste of space...but I wanted to see if this was simply an effect of how I run my game.

So how you all feel about these powers?

 

[Shroomy]

We haven't fought any monsters that could turn invisibile, but we've had a lot of experience with concealment. I could see how these powers could be useful.

 

[Piratecat]

My PCs have fought several monsters that were invisible They'd really like those powers, please.

 

[blargney the second]

It's the kind of ability that's nice to have one or two of kicking around in the party. I wouldn't look for it as the primary effect of a power, but I certainly wouldn't kick it out of bed.
-blarg