If you leave the chrome on:

You will hit it with the sander somewhere.

You may be able to see places that did not get painted well, under the edges of the chrome.

You may have runs coming off of the chrome, since it will cause the paint to be heavier close to it.

If you have any rusting starting under the chrome, it will show up eventually.

You may eventually have paint peeling, starting under the chrome.

If you have any dents next to the chrome, your repair will be difficult.

If you block sand the primer, the chrome will make it harder.

Are you starting to see a pattern? It is easier to do a nice job, if you take it off. That is why good paint shops don't mess around....they just pull it all off without hesitation. It really depends on whether you want it to look like a great paint job, or an amatuer job. Your choice.