I have 5 debt-free houses. The benefits of having multiple player characters certainly outweighs the negative (having less island space). One of my favourite benefits is NMT hoarding. I have 4 PCs stock up on Nook Miles and then print out loads of NMT whenever I decide to go island hopping. It really is a good way to island hop, well, at least for me.
The other most useful quirk I find with having multiple PCs is abusing the NPCs...Certainly getting more Redd art is a positive, but it also works with Gulliver, Saharah and Celeste. Gulliver has a 50% chance of giving you a hat, so having multiple PCs can even the odds a tiny bit to get the good furniture. If Saharah has a good wallpaper and flooring, having many PCs is good for stocking up. And finally, many PCs can help with Celeste DIYs. Other than the obligatory star wand and zodiac DIYs, you can have another PC collect Celeste DIYs for trading.
The other most useful quirk I find with having multiple PCs is abusing the NPCs...Certainly getting more Redd art is a positive, but it also works with Gulliver, Saharah and Celeste. Gulliver has a 50% chance of giving you a hat, so having multiple PCs can even the odds a tiny bit to get the good furniture. If Saharah has a good wallpaper and flooring, having many PCs is good for stocking up. And finally, many PCs can help with Celeste DIYs. Other than the obligatory star wand and zodiac DIYs, you can have another PC collect Celeste DIYs for trading.