phpMyAdmin is very widely used tool and it does not help it attract developers. Only Marc is currently active developing, I sometimes commit few lines of code and I don't see much other activity. Isn't among users some skilled PHP developer who would like to improve our code? Or phpMyAdmin already reached perfect state? I don't think so.
There seems to be big barrier in those projects to attract new developers. They both lack developer documentation, what is unfortunately quite usual in free software world. But is it the real reason? It probably discourages people who look at the code and are not able to understand how it works. They could ask on mailing list and they would get some hints, but this is probably too much for somebody who wants to fix some small issue. So this is something which can be improved and might help.
I also thought that open version control system can help also a bit in this situation, but phpMyAdmin doesn't seem to profit much from this. Gammu never had it (except of my own), now when I will be creating releases, it will have it, but I doubt it will change anything.
I'm really out of ideas how to attract developers, and looks like I'm not alone, as I saw recently, KMobileTools have same issue and there are definitely more such projects…
BTW: Anybody interested in improving mentioned projects? Just contact me or any team member :-).