Their other criticism is the usual lack of 'recognisable' musical instruments. Here I'm careful. There is a lot of techno that's been made with real drums, real guitars, riffs lifted straight off someone else's pop, rock or metal, or sounds taken from real life. It's not too far to jump before you have to criticise people putting microphones on violins to pick up acoustics that would otherwise be missed, or putting flangers and wah-wah pedals on electric guitars (which already have magnets inserted in them and do not resonate acoustically anyway) to make something sound 'cool'.
Of course, the real point here is that we're making sound. Your mechanism may be a piece of hollow wood, or a piece of shaped metal - mine might be the flow of electrons through space, or a digitised waveform no earthly machine could naturally produce. Then there's the experimentalist's argument: there are far more things you can with sound when you're not limited only to instruments invented more than three hundred years ago. When you can play around with electrons (in both digital and analogue interpretations) and use the power of intelligent machinery, then you can achieve far more complex and subtle things than mere oboes, triangles or celli can produce.
There's a third point, really, and it has to do with the purpose of techno. I find that I can listen to a lot of techno and enjoy it, but the best stuff makes me want to get up and dance. Most ravers can identify with this feeling. The primal urge to shake yourself about in time with the beat of the drum must be plugged into our hindbrain, instinctive and unconscious. When you walk into a rave and you can feel this incredible electric vibe sparking from the crowd packed into the booming chamber - the life-force of a hundred people amplified by synergy and thrown at you like a benevolent hurricane - you realise that there's something more to techno and raves than just simple appreciation of music.
Techno doesn't have to be boring or predictable - in a way, I find it a medium for progressive change in smooth increments (over other forms of music that vary their ideas in blocks). Some tracks that I like have the same idea over and over, repeated each time slightly differently - sometimes building into a crescendo of energy, sometimes shifting like an aurora. Others have more traditional ideas - repeated sections, variations on a theme, but do them in techno ways. Either way, techno and its affiliated musical cultures shouldn't be classified as a stale and repetitive. Listen to Ravel's Bolero and tell me that all repetitive music is boring...
Interestingly enough, I see a lot more good vibes and aspirations in the themes of techno than I do in the rock and pop culture. This may be a personal judgement, but too many rock songs are about sadness, pain, problems and strife. While hardcore and bits of acid tend to also use this societal angst suffered (or, as I sometimes feel, borrowed) by the current generation, techno has a much more 'join in and have fun' attitude. I think this is both due to the way the DJs and artists focus their energy, seeing producing tracks both as an uplifting experience and generating fun stuff for partyers to dance to, and to the crowd itself. While the drug culture of ecstasy and acid has obviously influenced some artists and ravers, I think a lot of people who listen to Techno want to leave their problems at the door and have a good time.
Must be a good thing.