Mmmmm no.
The problem with this is that cubing is still so young that even if it were a good idea, it would still be years before it could be implemented well, as times are improving very quickly even still. (well, relatively quickly) So as a result, you'd have to constantly update the titles.
And don't we already have something to strive for? Namely, the sub-x thing that you yourself mentioned. People in chess don't have a definitive thing that they can strive for, like most games won or whatever, so they need the rankings. We don't. We have a definitive, hard as diamond set of rankings based on how fast we are (mostly).
So we can go for getting sub-whatever, and those are our rankings. Instead of some pretty arbitrary thing which has a hard to understand number which somehow indicates a measure of skill, we can look at our times, see who's above us and see who's below us, and do our best to keep improving.
It just seems like a pointless and bad idea, frankly. Sorry.