it allows you to have a set of mouseover macros for raid healing... and target heals for well... target healing;
Elsewhere I always used just one set of macros with conditions built in. Check for a mouseover target, if it exists, cast on them. Otherwise check for a friendly target, if it exists, cast on them. Otherwise check for a friendly ToT, if it exists, cast on them. Don't know if Rift can do this? But I'd hate to have to find space for two sets of buttons. I haven't gotten into it much in Rift because I'm not doing dungeons/raids and don't have to worry about a tank to heal. I just use mouseovers for my friendly spells and keep the enemy targeted for casting unfriendliness.
Edit: or you can just build modifiers into the macro, which I'm pretty sure Rift can do? No modifier for mouseover, shift for target, ctrl for focus or ToT, alt for self, something like that. Edited, Jun 15th 2011 9:51am by teacake