Extending the time it took to switch weapons was good, early on there was no reason to think about your positioning or what weapon you had out, you would push spears or archers who just insta switched, kited, shieldbashed, then when some distance insta switched again and used their ranged weapons. It was incredibly cancerous and didn't reward melee (the fundamental core of the game).
However, I feel that making it so you couldn't switch mid attack was a really unnecessary change and feels awful and clunky. Spears have a relatively long attack and it feels like the game isn't registering your input at all when trying to switch. There is a similar issue with the "bump" mechanic on ranged weapons, where the game doesn't let you switch weapon but also ignores your inputs trying to switch it, until the bump animation is over. It's frustrating because you can end up perma-stunned and unable to switch weapon.
Just odd decisions frankly and long overdue for change. The kind of issues playing Warband for 5 mins would have rectified also.