3000' has historically been used as a minimum recovery height for abnormal flight, in many countries. I think it originated in pre-WW2 military flying training. As others have said above, in aircraft of an earlier era, 3000' really was barely enough to be safe - when aircraft would spin without hesitation for example. Nowadays I can think of some aircraft which also require more than 3000' to safely practise stalling.
Is 3000' excessive today? In some cases, yes. (I'm thinking of an aircraft which is highly spin resistant, a pilot with enough training to have ironed out basic errors, and a real need to be lower - not just "because I can"!) But in my experience, the pilots pushing for a lower height are the ones who should stay high, for human factors reasons. If you follow my meaning.
Anyway, a competent instructor will usually not have to waste time & money to get to 3000'. There are things to do on the way up and on the way down again.