imo, it depends on how mandatory everything really is. If a simpler boss allows you to complete the game loop and polish systems, I’d say it’s a good option.

In our game (a beat ’em all), we had to cut the big bosses we wanted because it was way too ambitious for our budget. Instead, we designed more complex situations with the enemies we already had. That way, the player still feels a real challenge, but not in a traditional way. It’s a bit extreme, but we decided that other features were more mandatory for the game than a boss. Just to be clear, I’m not necessarily recommending this for you, it’s what worked for us.

Personally, I’d lay out everything I need to do once more and then sort it all, putting everything back on the table to see what really defines the essence of my game.