well, I never said it was greatly 'designed'. In pve it was fairly easy, sure. 70% of the time it was whack-a-mole with the healbot. It was fun to play though. It made sense and you felt powerful. Aura mastery was a powerful raid cooldown, as was divine sacrifice and hand of sacrifice, and using them properly could make a big difference between average joe and a skilled player. Not just 3 buttons.
Edit: And Hand of...Something. Can't remember the name. Reduced threat by 2% every second for 10 seconds. Having to keep an eye on threat meter and tone down some peoples threat while allowing them to keep going ham. (cuz it was possible for tanks to lose aggro back then) Or stop one tank overaggroing the other shortly after a necessitated switch. Stuff like that felt good.
Divine plea reduced your healing output by 50% for 15 seconds, in a progression fight that's quite a long time to be not doing much, couldn't use it totally mindlessly.
Like I said, it was fun. I don't think more buttons = more fun necessarily, and I wouldn't use that as my way of measuring it. I hated paladin after wrath because of the introduction of holy power, and stupid amounts of RNG that could affect your healing throughput (think they toned it down a bit after cata but when I was playing it, it felt horrible.) I tried my paladin the other day and I just don't get it. I don't think theres anything wrong with something being simple yer powerful. It just feels unsatisfying now.