Another example of one line in the spell description making it useless. . .
Back in the 2e days, I was playing a Wizard (actually, only the 2nd D&D game I'd ever played in, and the first wizard), and I'd just got Conjure Elemental rolled as my 5th level spell.
So, the first time we get into a fight, I was itching to bring down an Earth Elemental on somebody, so I start casting. . .
The DM reminds me of the casting time, "1 Turn", and for those who don't remember AD&D, that means 10 Rounds. So, I spend the whole fight casting my spell and by the time it's cast the fight is over.
The whole experience turned me off of summoning spells in D&D, I never got into the habit of using summoned monsters after that.