IPS doesn't prevent total concealment (Seeking enhancement does, though). The benefits of it I most often enjoy are ignoring less than total cover (like, say...the almost automatic -4 you take for soft cover because your allies are in the way of the shot) and being able to shoot into a grapple safely. Get a +4 dex item and you only need a base dex of 15 (my sample point buy left you with 16). Dex has lots of benefits other than ranged attack rolls, it's not a waste.
And "invest" sounds like such a loaded term... all you did was lose 1 skill point per level in return for ending up with a modest str 10 (and the better dex), that's barely a loss at all. If you're starting at mid levels maybe str is useless. If this were a build actually starting at level 1 I'd never in my right mind eat a -1 damage penalty (or use a crossbow when I have a perfectly good Rapid Shot feat) for the first several levels of the game.