I'm torn here. On the one hand, yeah, a 2 XP weekly cap seems insufficient to motivate people to play.
On the other hand, in 2e, even 2 XP is a lot. 2 XP every week means two dots of Disciplines (if they're in-clan) every three weeks. No scaling costs means people are running around with multiple five-dot powers within a couple of months. I'd contend that the game isn't meant to be played that way.
For gameplay purposes, I like something similar to @Tempest's proposal as well. Use a fairly high floor and a fairly low ceiling. I also want to explore the idea (similar to what we did on CoFaB toward the end) of having deliberately asymmetric starting points. If you want to play an older vampire, you start with higher BP and more discipline dots, but also lower Humanity etc. That only work if it's paired with slow and/or capped XP gain - if everyone gets a ton of XP, then the different starting points don't actually differentiate much because people can just buy whatever they want to level the playing field anyway.
The goal, then, is to find something other than XP to motivate people to play. In Vampire? Make people work to earn blood, or territory, or Status (it seems like every Vamp game eventually decides to make Status stop costing XP anyway). Create opportunities for advancement that A) aren't tied to XP and B) aren't permanent - you have to work to maintain them, which means newer characters have a fighting chance to catch up.
