For better or for worse we wouldn't keep anything closed source, it goes against the whole spirit of crypto (besides the fact open-source got us here in the first place) but even more importantly from a realist perspective any closed-source service or wallet dealing with money of any amount simply would not be trusted.
One way around that, sort of, which was discussed in the Drk coin thread early on, is to have a trusted 3rd party audit the code. Finding a trusted 3rd party, and if that would be good enough, is a question though.
For systems that are truly unique, a coin does sort of need to be closed source, at least to start with, or P&D clones will just kill whatever is unique about the coin. And probably do a poor job of implementing the 'unique system' to begin with.
But I agree about the forking thing. You can't hardfork Noble repeatedly, trying to catch the latest fad. The partner coin idea could potentially work. One problem is the fact that people may not really care about any features really. They say they do, but in reality all they could be doing is jumping from one pump and dump to the next, using new features as a context for the pump. It's the same reason why pumps quite often occur on the flimsiest of coin news -- listed in coin market cap, listed on new exchange, listed in some obscure article that nobody will read anyway, nation coin does airdrop, etc. It's just a reason for a pump, so people may not care so much about whatever feature is in fad right now ... it's just a way to make money. Exceptions would be things that are truly unique and serve a purpose, perhaps anonymity, true anonymity, coins like Ethereum or MadeSafe (in theory), that sort of thing.
One thing that could help Noble, and for all I know has been implemented and I missed it, is to incorporate the marketplace into the wallet, as well as have it set up for both android and ios. If you have discounts or marketplace news, it can then appear as a popup in the wallet itself. It's one way to get the marketplace more attention and be a bit more unique than other coins.