Bad collision is one of the long-standing issues for Morroblivion. Hashmi fixed a lot of meshes in his Collision Redone mod, but there's still more (a lot more, in fact).
Probably about 70% of Morroblivion meshes still use collision from nif converter, which is uncompressed bhkNiTriStripsShape and is VERY BAD. In addition to that some of the settings at bhkRigidBody block are incorrect.
For statics this collision should be replaced with MOPP shapes and in some cases made more precise. The reasons for that are:
Performance. I'm betting collision is responsible for 2\3 of performance issues with Morroblivion.
In some interiors there are Havoked items on shelves very close to walls. When collision on the wall is imprecise like it is now, such items clip into it and then end up moving in strange positions or falling outside the cell altogether.
Havok materials. This is what defines footsteps and weapon sounds and whether or not arrows will stick in object or bounce off. Not the biggest issue, but still.
Unfortunately, collision must be fixed manually, one model at a time (or at least I don't know of any automated utility which could help). PyFFI can convert collision to MOPP shapes, but it makes things even worse in some cases.
We are talking about thousands of models here (hundreds if we reduce it to only the most essential ones).
I have written a tutorial on it.
Model sets, which still need fixing are listed below.