I don't see anything wrong in Bitcoin being dominant.
It's the oldest, strongest and most valuable cryptocurrency and it deserved to be on a throne. Afterall, it took this place because of the users who suport Bitcoin through all this years and huge progress it has made.
On the other hand market is open and every other coin has the opportunity for success although I truly doubt that some other coin will ever achieve such success.
People just want to complain that is all, they want their favorite projects to have huge market caps without really deserving it, it is very easy to wish that the projects in which you invested go up in value but if they do not have anything to offer to the community then I do not see why that should be the case and the market agrees with me, there are thousands of coins out there but only a selected number of those coins are appreciated by the community as a whole.
And this happens because most coins are just copying what other people are doing without really integrating any kind of innovative ideas to their projects that can make them better.