Physics is observable reality and Mathematics is one of the tools of observation and description of physical reality.
Mathematics is all tautology, so to speak, as it is inherently true....in other words, it is true because it has to be true since that is the only way mathematics (and logic) could possibly work....
As physics becomes more and more mathematical, we more closely approach the notion that physics is all tautology...that should greatly appeal to you, since it would prove that there is only one way the universe could possibly be structured (a notion that generally appeals to deistic thinkers)...of course we aren't there yet: for example, we have yet to derive certain physical constants, they simply are observables for now....
With that in mind...
You can't criticize String Theory because it is purely mathematical, yet support Quantum Mechanics which is also purely mathematical...
Physics is WYSIWIG – What You See is What You Get String Theory is WYTITWIRL – What You Theorize is Totally Worthless In Real Life
There was a time where Quantum Mechanics fit into the "totally worthless" category...we had yet to confirm it through multiple experiments and the theory had thus far yielded no practical applications...
Today however QM has practical applications...it has allowed us to prove why atoms bond the way they do by describing how electrons fill energy levels...it has explained the double slit experiment with light and the wave-particle duality....it has given us insight into the strong force and why certain nuclei are unusually stable....it has explained why neutrinos change flavors and if neutrinos were to be shown to be capable of FTL travel, it is ready to explain that via the mass eigenstates of neutrinos...I assume you are aware of most or all of these things...
All those things are purely mathematical, yet very real and confirmed by experimentation (in the case of FTL neutrinos, could be confirmed by experimentation)...
String Theory, to my knowledge, has not yet yielded any applications, but QM didn't either right when it was developed...furthermore, a theory being purely mathematically is poor reasoning to condemn it...you would be better off questioning its testability or using the argument of economy instead of disowning it because it's all math...
As for ECE, I never seen anything supporting it beyond a "personal" webpage...
FYI, the general feeling amongst the scientific community is that gravity is not a true "force" but a result of bending/warping/distorting space-time (mass being the obvious suspect for why this distortion would occur)...therefore, it is likely that attempts to "unify" gravity with the other forces are completely futile...