I'd like to gingerly suggest that you carefully reconsider any advice you get on a message board about the propriety of directly contacting customers and prospects. Message board nerds like us are terrible at evaluating these situations, and it really holds us back.
Out of those 100 customers, 81 picked up the phone, and of the 81 that did, exactly 3 didn't want to talk to me. The rest graciously provided amazing, actionable feedback.
Do not make the mistake of listening to a bunch of really smart, technically-inclined HN'ers when it comes to business advice -- unless these are the guys you're selling to. Everybody, no matter how savvy, is really bad at predicting how a market will react. You just have to do these things and see for yourself.
So what people really hate is an annoying phone call by a sleezeback asshole (which, I admit, is everybody in sales).
So maybe the real lesson here is that people don't hate what you do, so long as you aren't an asshole.