Why is the default to be "spending badly"
It's a nonsense, apologetic defence.
Sign players who improve the team or heaven forbid, allow some depth.
That isn't asking much.
And your last sentence isn't accurate, as much as the Sky Sports type agenda would love to have you believe. The stadium, previous board and Russia's war got us into the current situation. Sure, one window under Koeman we spent a bit of money. Like Fulham, Bournemouth and West Ham have since. And nowhere near the amounts Nottingham or Villa have.
Teams spend money, teams invest money into the playing squad - we haven't. The only team to not have done the last 4 years.
Our squad value for fees, including players we have on loan who we didnt actually spend is 19th from 20th. I think Ipswich actually went above us this window. [Edit. They haven't. Our squad cost is 19th in the league, above only Ipswich.]