Biggest bottleneck for me in terms of Lightning: You have to pay to participate. And quite a lot, too. The UX is also ... questionable.
It's fun as a "Twitch Bits but open source and free" - but if the easiest solution is a custodial one, how different is it, really?

I still run my CLN node, I had a lot of fun with it, but I won't exactly miss it. A little while after spent my sats via Bitrefill, I lost my channel due to an LND bug force-closing the one that Fishcake had gifted me.

Ripped me straight out of the network and... yeah, that was that. Now it's just ideling. 

 The moment there is risk of losses it becomes useful only for zaps. Tiny amounts. 
There are no risk of losses at base layer. Layer 2 is supposed to be more reliable, not less.