The negative reaction might have been precipitated by any one of three different elements of your question.
Firstly, while I don't see any obvious flaw with the core question about which kind of dash should be used if you're choosing an unorthodox writing style that uses them for dialogue, the way you presented the question - "I have always use [sic] the hyphen when introducing dialogue" may have been a bit confronting. The reaction might have been along the lines of "that's not standard English so this is a bad question." Even the title seems to presuppose that the three options are acceptable alternatives to orthodox quotation marks - a view that some at least might disagree with.
In this particular case, you might have diffused some of this negative reaction by reminding everyone that punctuation is a matter of style rather than grammar - and perhaps linking to a few answers by senior users who often make this very point. Perhaps emphasising that you acknowledge the standard approach to dialogue but you're interested in alternative styles. Are there any famous works in English that use dashes in this way? [Emily Dickinson used ubiquitous em dashes, but not for dialogue per se].
Secondly, you added "Also, a little side question. Is it normal, and acceptable to use hyphens and dashes as dialogue starters?" It's possible you may have received a downvote for this: questions should not, as a general rule, have multiple components or "little side questions". Stick to the issue in the question title.
Lastly, your closing sentence "I'm not looking solely for your individual opinions, as that is off-topic, but rather numbers on what the majority prefers" [my emphasis]. Uh-uh, that's a survey, and definitely out of bounds.
So unfortunately, your interesting question included multiple triggers for a negative reaction.
However, don't be dismayed! Your question also had many positives: you received 4 upvotes, there was useful commentary, and your question resulted in two answers, one of which you liked enough to tick. You've asked for advice here on Meta, and hopefully this will assist in eliminating the danger points in future questions. Don't be put off by downvotes, and keep honing your craft as an ELU user :-)