Hinata isn't nicer than Sakura she's just inresponsive..has no opinions. Those boys just want a doll with boobs not a person.
Yeah, a lot of guys who claim to "hate" Sakura tend to be beta males who are afraid of women who actually have their own opinions, their own ambitions, don't "need" men to be "strong" (*looks at SAO girls*), can stand up for herself, can't be controlled, etc. and/or are hypocrites since I'm more than certain a lot of them like girls who are just as, if not more tsundere than Sakura is, like Louise from Zero no Tsukaima, Taiga from Toradora, Kagome from Inuyasha, etc.
Outside the computer, I openly admit that I'm a beta male. I'm not outgoing, a leader, dominant, (want to be) the center of attention, have big ambitions, etc., but it's really because of that that I actually prefer stronger, more open, friendly, etc. (taller is nice too and, of course, not controlling and such) girls like Sakura, Anko, Tenten, Konan, Kushina, and such - in terms of Naruto - that helps balance against me whereas Hinata, while physically pretty (not exactly "hot" or "sexy", IMO), would really, aside from the creepy stalker bits, just be boring in a relationship for me because she's essentially just a "yes man" doll. All I can imagine if we were on a date together would be really long periods of dead, awkward silence between us since I'm not good at starting conversations (at least unless I know there's something the other person and I both like) and Hinata is just not good at talking, period.