headstock tuners are fine in your home studio or if you are just dinking around
the reasons for the rage are as follows:
1. people not muting their guitars while tuning with headstock tuners on stage
2. headstock tuners make you look like a TGP dork who wears birkenstocks with socks and a tommy bahama shirt while playing "la grange" at the county fair
3. headstock tuners are (for the most part) cheap and inaccurate, although there are some higher quality ones
4. they look like a giant herpe on the headstock of your guitar, which is fine for playing in madison square bedroom, but live performances in front of actual people are about aesthetics