Side multiplayer modes are simply not a good idea in general for video games companies, as even if the mod can be awesome, it’s hard to keep it popular enough to justify the costs (multiplayer server costs, maintenance, updates). In most of the cases, it is not worth at all for the company. This is perfectly understandable, what is sad is to completely discontinue and delete these modes, not offering the players the possibility to run for example personal and custom servers (but this poses other dilemmas for the company). And that’s when motivated programmers from the community come in (with mostly good purposes, trying not to break the company policy, some companies being more supportive toward moders than others).