The problem is that anchoring to even steel studs will not take all them much weight without blocking to spread the load over a larger area.

The folded edge of the stud will flex under load and the drywall start to crack around the attachment points.

Bookcases would likely be a better option, or some vertical supports to the floor from the shelves to transfer some of the load.

Even relatively small cross sections of hardwood usually have a high load capacity vertically.
You could use small 'posts' at the front and back of the shelves to get weight to a lower shelf, and finally to the floor preserving a lot of the 'open' appearance.

Even a 1 inch x 2 inch 'post' from a decent hardwood has incredible vertical load strength (parallel to the 'grain'.

You do not need 2x4s hardwood sections for something like this.

You really need to contact your landlord before either painting or drilling into the walls. Most would have a conniption fit and initiate eviction ASAP. And don't think that he won't find out either.

Thanks but the landlord knows all about it.