If a fixture is broken and it is one of a group of matching light fixtures, or the fixture is a required style then it is often approriate to repair the light fixture rather than to replace it.

If a suitable replacement fixture is available and can be bought at a resonable cost, then it is sometimes better to just replace the fixture with a new one.

Time spent repairing a fixture needs to be justified. If a suitable replacement light fixture just is not available, or the fixture is a special one of a kind custom made piece then repairs to the fixture may be justified.

Of course there are always the light fixtures that just are not worth repairing which is sometimes the case, so it just gets replaced.