They're targetted more at productivity than gaming. I have a 3415 and frankly I want IPS for colour reproduction and accuracy for photo processing and the like. I do game on it but don't have a problem with 60Hz and don't need G-Sync if the graphics card can always produce 60fps or more.
I'd actually wager that the majority of the Dell ultrawides are sold for productivity applications rather than gaming so that's where their target market is. They're happy to leave the gaming market to the likes of Acer.
You're right of course, but I don't understand why Dell are staying away from the gaming sector. They have done well with the S2716DG, and they have a very reputable name when it comes to monitors with MANY people who'd snap one up in a heartbeat, as Aaron and Wulfster attest to. They'd clean up if they had a competitor to the X34.