Ruin Explorer
Legend
This could not be more true. Most monsters in 5E are a little on the flabby side HP-wise anyway, they could afford to lose a few - it's better as you say to have other things protect them (especially tactics) rather than making them even more of a giant bag of HP.Generally, just increasing the hit points does nothing to make an encounter more interesting.
I do appreciate some DMs are dealing with some very hyperoptimized DPR characters and may need some cushion though!