Holy has some core thoughtput issues. It's sole regen comes from spirit. While a disc priest, holy paladin, restro, even shaman to a degree have ways of regen mana that aren't spirit. This leads to holy priests allocaiting 4k or so secondary stats to something that doesn't make them heal for more, it just lets them heal period. Thats far behind the others who can get plausable income just from manapool size.
TLDR: If holy got spell power from spirit it would totally help.
[Today 06:48 PM] Ion:swimming in a natural body of water ISN'T acceptable...it's momentarily tolerable