Budgets aren't infinite. Huey's have proved over decades to be a reliable and effective aircraft when reasonably well cared for and flown with a modicum of good sense. One of the nice things about a UH-1{whatever} is that there's a substantial body of "corporate knowledge" and "this is what works" information available.
I don't need a Porsche for my drive to work. Maybe the MoD in Ukraine figured out that they don't either.
It's been over three decades since I flew a Huey. I'd love to fly one again. May the UH-1 live forever.