I have the feeling, a lot of these discussions go in the direction of blaming peoples (GCs, TCs) or countries (Greece, Turkey, UK, USA) for the Cyprus Problem. In my opinion, it would be a better approach to blame situations.
I think Cyprus is to be seen, first of all, as a part of the wider Eastern Question. If Cyprus hadn't been a british colony, the Cyprus problem would most probably get solved around at the same time, in the 1920s, and in the same way as the greek-turkish problems. Cyprus would either belong to Greece or to Turkey or it would be split between the two, with GCs and TCs falling under the regulations for the exchange of populations.
But, Cyprus being a british colony, this happened in a slightly different way some decades later, also being influenced from the new situation, i.e. colonialism and anti-colonial struggle, Cold War.
There isn't much point to speak about what is legitimate. We may say that Enosi was a fair goal, based on principle of self-determination. But in the same way, we could say that the formation of enclaves and a demand for autonomy or even union with Turkey, can also be an expression of self-determination since TCs were the majority there. However, the RoC-government didn't accept this.
The basic mistake was that we accepted the nationalism that came to us from outside, and the split of the Cypriot society into Greek and Turks, who both defended above all the interests of their respective nations. After this happened, it was most probable that the Cyprus Problem would be solved in a similar way as the greek-turkish problems earlier. The exact way would depend simply on balance of power - and as this leaned towards Turkey, we had a solution more favorable to the turkish interests.
This nationalism left no chances for a common anti-colonial fight with the goal of independence. And the colonialists could use this split for serving their own interests.