I think by gay, they mean wimpy. Now there is no style of music that doesn't have something good in it somewhere. But it's usually the innovators and originators who capture the energy and integrity of a style. Those that come later are by default less original.
There is something in the musical language that can cause music to be wimpy. Uninteresting and overused chord progressions, weak compositional form and lack of understanding theory are all contributors to music that is boring.
For Ambient, some of the innovators were Brian Eno, Harold Budd and the German band, Cluster. Cluster was electronic before digital. Kraftwork gets a lot of credit for that, perhaps deserved. Gong had some cool synth stuff in the early 70's but they were more psychedelic. The post punk pop band Wire is credited with being pioneers in electronic dance music. Bill Laswell was in the forefront of Drum 'n Bass and Dub styles as well as experimental. These were not wimpy musicians.
Because they are great musicians.
There is so much electronica, and a lot is done by people who are computer geeks, but not trained musicians. They all bore the crap out of me. Music has a vocabulary that must be known and understood, regardless of the genre, to be great.
So in some regards, your critics may not be completely wrong. But it sucks for them to say so.
And it is not because of the "kind" of music it is. It may be the artists you listen to are not the best musicians. Keep exploring. You will find greatness if you seek it out.