In a game where rests are player driven (leading to the 5MWD, but that's another issue), having a lot of unspent resources means that you failed your team. You held back resources that should have been spent to help the party overcome challenges, causing a long rest earlier than otherwise needed.
Depends on how you define "overspending." I will agree that poor use of resources is just as bad, but people value resources differently. HP is technically a renewable of resource, since you recover 100% at the end of a long rest, but most players seem to value it higher than spell slots (which also recover fully). How do you gauge the value of a utility spell that could (theoretically) be done without magic? Because of this, I find players seldom truly overspend resources (not to say that I haven't seen a wizard waste a fireball on a lone goblin).I take your meaning, but depending on play style, the opposite can also be true. That overspending resources could lead you to needing to take a rest earlier than otherwise needed.
Which way you feel about that gets to the heart of the poll question, I think.