There's a difference between decentralisation and fragmentation.  You can have a system that is decentralised, but if you have many mini-systems they wont be very decentralised, nor secure by definition; and much utility value comes from the network-effect of the larger system also.

It depends what you view bitcoin is, but I've come to view it as a generalised unit of proof of work measured in normalised electricity x time.  And from that point of view it doesnt seem possible to make a new unit, only to improve the unit (if its still an electronic proof of use of electricity at a given time, its always a bitcoin definitionally as it is the word to describe that thing).  As in the parable marking a bitcoin (a standardised electricity-time unit by definition) with a logo or brand and trying to sell it for above par with branding isnt creating decentralisation nor value.

Btw its really hard to improve bitcoin algorithmically or protocol.  The implementation has some known things left to improve, and they have a pretty comprehensive wishlist.  If people  want to work on improving bitcoin there is a github, developer mailing list, etc.  They're always looking for quality assurance, code security review, documentation writers, and protocol & code review.

Adam