There is a concept in gaming known on TV Tropes as Complacent Gaming Syndrome, where eventually all the best players end up playing the same way, with the same strategies, same equipment, and same plan - because it's "optimal." The problem with this is the same as the problem with a dominant species subjected to altered selection pressures: one exploitation of a weakness and the whole thing topples down because nobody can cope with it. Plus, it's boring.
It then follows that everybody expects something new with no weaknesses whatsoever, or something that is bigger, faster, stronger, better. A new standard of optimisation, a new level to aspire towards. The risk is that it then leaves the older ways in the dust. This is called Powercreep. Perhaps the reason the Diamondback is receiving the criticism it has is, because we are all so used to seeing the Asp and Anaconda dominating the exploration game, it isn't powercreepy enough? For another more serious example, ask yourself why there are hardly any Eagles and Vipers being flown by advanced players.
The key to combating both of these phenomena is to provide variety at all levels, and a reason to embrace variety. Personally, I prefer flying a Cobra over an Asp because a Cobra can run rings around an Asp, and it is easier to control, plus it's so much prettier. Plus, for what I am doing I don't need an Asp just now: I own one, for sure, but when the time comes to require that one be used, such as mining or going out beyond the most distant spiral arms, then I'll use it. However, these are still such limited options right now in the exploration game - trading has the Lakon and Faulcon DeLacey options and the Clipper, combat has Vultures, Fer de Lances, and all sorts of other options - and with limited scope for providing reasons to use other options.
I had wondered if the Diamondback was the start of a measure to introduce such variety in roles in the exploration game at first at the Cobra level - a Cobra with better jump range and better fighting capabilities but less scope for self maintenance and survivability, indeed a form of the very "glass cannon" described above - while in the background providing a reason to use them (Them Aliens). Still, it's only day 3 of the beta for an update to a continually improving game, and we still have another half dozen or so other ships to come as promised further down the line. We may just have to wait and see what these tomorrows bring.