The synthesizer, especially in modern rock music, has a bad rap. Of the few rock bands that use a synthesizer today, most of them use it for the same purpose it had for most of its life - a glorfied electric piano, organ, or a device for making spacey noises in the background. Few bands treated the synthesizer as an instrument until the rise of Disco. Then, cheesy synthesizers were pushed to the front, making people dressed in leisure suits and platform shoes shake their groove thangs. As the synthesizers evolved, so did the music. Synthesizers were prominent in the pop music of the 1980s, popularlized by New Wave leaders like Devo, The Buggles, and Gary Numan. Yet, when the 80s ended, it seemed like a silent anti-synth backlash hit.
The blame can really be pinned on how people used this new toy. Rather than harness the power of synthesizers to create new sonic textures for music, musicians were trying to bend the instrument to what they were used to. They ignored the potential and just synthesized orchestra hits, cheap strings, lousy saxophones and the like. The only instrument a synthesizer has been able to replicate well, without sampling, is a simple piano. No wonder people dismiss much synthesizer music as "cheap". It's obvious you can't get the best use of a synth by just trying to replicate something else. The pioneers knew it. The electronica artists know it. Time for rock to catch up.
Experimental musicians have always played with new sounds. Listen to some of The Residents early (before God In Three Persons, but after Meet The Residents) albums. They too were new to the synthesizer but were willing to try and see what it could do. They used one of the first samplers to bring new, unique sounds on the road - the ones they made with homemade instruments. They used the new technology to do what couldn't be done before. Others have done the same. Early Kraftwerk, and Neu! for example.
Of course, experimental music doesn't sell to the masses. So, rock music, if it tries to cater to a large audience, sticks to sounds that have been established. Space-rock, ethereal sounds, or that good old electric piano. The growing audience for electronic music, where some of the unique sounds of synthesizers have taken off, has lead to a bit of sonic crossover. Yet, the bands that use a synthesizer still stick with what is mostly tradtional. Fortunately, music development is an evolutionary process. Rock will use the synthesizer to its full potential. It just needs to embrace it fully, rather than ignore it, or just treat it like a toy.