ELT is not a problem, yes, problem is people trying to use everything at once without turning on their brain and questioning themselves whether it is really the right way.
Another thing is simply a question of balance and application, let's face it - Destruction is simply not very good at padding, thus numbers are lower across the board than let's say Aff/Demo/Spriests/Whatever which can produce a bunch of often meaningless damage easily simply by autocleaving shit or tab dotting one way or another.
Destruction IMO is quite a bit more viable than, for example, Padffliction or Demo for where it actually counts, namely switching to and killing priority targets, the biggest "issue" with it that it offers a highly focused damage instead of damaging everything around at once by a fraction, which results in warcraftlogs numbers not looking nice enough.
Another problem is an absolute dogshit theorycrafting community for Destro, which leads many people astray, stumbling over their feet trying to pull out bullshit rotations which only a machine in lab environment can perfect - namely RB/CDF + a bunch of other crap, which was kindly suggested by various people around and is religiously being parroted by various uninformed individuals.