These expansion joints are easily removed because they are put on wrong to begin with. The joints are supposed to be put on first, then the lath. It is a lot faster to put the lath on first. Putting the lath on first limits the movement due to expansion to none.
We filled in the joints with my flex-con mix, and then coated the whole wall.
If you haven't seen our method for re coating painted stucco, here it is: Recoating old stucco, painted and unpainted
Putting on our color cement finish coat. Sure looks a lot nicer without expansion joints.
There is no such thing as expansion joints made by a stucco manufacturer. USG, a large manufacturer on expansion joints says that there must be a gap in the sheathing for the expansion joint to work. I have never seen such a gap. This means all the expansion joints in the world are put on wrong.