The housing item slots do need to go up, but not to 1000. I think that is way too much because it will cause load times to be excessively slow and the lag.

I've done instance housing before and unlimited housing items for them. The instances where huge and the more items we put in them the more horrendous the lag was and loading into them was a toss of the dice whether you crashed or not.

I get why SE limits the number of items on the exterior, but 20 items is just too small. And for interior the current number is not enough, but you don't know what you asking when you say 1000 slots. It's a crash waiting to happen.

The graphical upgrades SE plans will happen over time. Maybe at some point they can allocate a reasonable number of slots to housing items for each size house. We can only hope and speculate.