Ignore them.
That's the best advice I can give you. It doesn't matter which job you picked and why, it doesn't affect their gaming experience.
AST is an incredibly strong healer, pairs well with both healers and has a nice toolkit to deal with all kinds of situations. Some people are understandly put off by the new card system and I know several controller players who don't enjoy AST because of the target switching but still enjoy the design and the aesthetics.
You have to work for your numbers, be they healing or dps. WHM is pretty straight forward in that regard while AST needs to plan and juggle more but there's really no reason why AST would be a poor choice. You may have to deal with some bias while leveling like tanks pulling tiny because you're an AST but if you know you can handle it and ask for larger pulls, most will gladly oblige. Unlike during the start of ShB...









