her title speaks for itself, first of all. APPRENTICE OF A SANNIN. dude.
second shes already shown to be able to react to and defeat puppets in sasoris army and formulate healing strategies that another entire village didnt think of. her intelligence is above par since she could do the written chunin exam without cheating. yamato said they have to protect sakura most of all because shes the only one who can heal them, and madara realised this too. since every opponent is gunning for her http://tvtropes.org/pmwiki/pmwiki.ph...tTheMedicFirst, you would expect some to at least respect her job as being extremely dangerous. tsunade even mentioned how hard it is to do training around bodies, blood, guts and poison and how they need PERFECT control so their hand doesnt slip and cut an artery.

would you walk into a military hospital and shout that every staff stationed there is useless? yeah probably not! in all likelyhood every one of those guys is every bit as dangerous and efficient as an actual soldier. particularly because they know EXACTLY how people die.

third of all, sakura has earned praise for both her major skills (medical shit/poisons and taijutsu) by extremely high level shinobi (sasuke, kakashi, tsunade, sasori, chiyo and naruto). are you saying ALL THOSE GUYS are blind dumb idiotheads who dont know what they are talking about, and sakura's really a weak little doll? ok...