People end up at the same power for end-game because they happen to be the best for end-game. Now, what you do to start and mid-tier is up to you and there are many more viable options. But for sheer amount of raw power at end-game, the options are very limited.
If it's boring you than feel free to use different sources, I still don't see how anyone else's power source affects you. There are not too many viable sources to choose from, and with the nerfing of UU matter by gregtech, those choices are limited even more. However you say "let's experiment" like you have some cool ideas for power generation, what do you have in mind Zak?
There are plenty of ways to generate EU without solars. The much maligned GregTech adds several types of generators that can burn many types of fuel. With a little work you can even make nitro-diesel from oil, and generate tons of power. Before building fusion reactors, my friends and I generated in excess of 4 trillion EU from nitro-diesel alone. Oh, and spamming solars, is both lame, and demonstrates a pitiful lack of imagination.
Alternatively, laziness/time-energy-efficiency. There are quite a few ways to make power, they alllllll take more work than solars.
Spamming solars in both quick, efficient and easy, and allowing people like myself to redirect their imagination elsewhere... I for one have not spammed hundreds of solars, or stuck to one power source. I am arguing on behalf of those people who have just started or haven't even joined the server yet, they aren't anywhere near getting there fusion reactor.