Reading through this discussion... I'm somewhere in the middle. The process of evolution isn't cheap, but it also isn't special. It's not necessarily something you "earn" so much as how far you get climbing your own ladder of potential, effort and evolution. The highly evolved are in leagues of their own and each step is significant. So, for a superhuman... evolution is everything.
But from a storytelling standpoint, it's cheap. It can be triggered whenever for virtually any reason the writer likes and the trick is to wield that weapon well. Each one exponentially increases the characters capability and it's always much more interesting to tie that kind of evolution as a narrative force with evolution as a character.
The fact that anyone could theoretically do it at any time, yet few ever make it past 3 (if they ever get there) keeps it mysterious and impactful and also makes resources such as Bramon's serum so important. The downside is that the audience won't always respond the way the writer would like to an evolution.
The do-nothing duo using it to evolve mid battle like they're popping an energy drink during the fight with Ella is kind of awkward in retrospect and doesn't properly sell what they're actually doing. Besides, where's the trance? But this was very early in the story and evolution hadn't even been properly introduced so... it's excusable.
Coles evolution can come across to many (including me) as a get-out-of-jail copout. I never found Cole intimidating. I never thought he contributed anything to the story or the dynamic other than calling everyone and everything a bitch or a cunt with nothing to back the attitude up. I did not enjoy beating him because I never found him intimidating or challanging in the first place. And his evolution only came out to a "Surprise, fucker. Now you gotta beat his ass AGAIN while he monologues at you" and he doesn't even die.
Can't land every shot you take. Other Evolutions have worked out far better. Like the MC in the battle against Klaus. It had a long build up, was a long time coming, and didn't happen immediately. We lost once and even then had to fucking work for it and it felt earned with the increased mastery of the MCs powers. There was nowhere left to go but up. Similarly, Alice's was a great example of good storytelling and informed entirely by her character, background, attitude and absolute refusal to be limited by virtually anything.