If you don't understand how much Multiplayer would add to RPG Maker, Neverwinter Nights would be something to try.
I'm not disrespecting RPG Maker. It is awesome, but multiplayer options would catapult into Legendary status. At least for me. And if we're speaking cost, I'd pay $200.00 for RPG Maker with that added feature. And trust me I'm not rich by a long shot.
We do understand the interest and value of Multiplayer - there have been more than enough requests for multiplayer-scripts and even tries to make those scripts from the community.
What most people who do wish for network options don't understand is that its an extreme amount of work to implement - basically the entire engine would have to be rewritten from scratch to implement multi-user-stability, fast data transfer, secure data transfer (to prevent someone from cheating ingame) and a lot more.
For example, the current engine works around one active map with the player, all other maps are static data to be reset and created only when the player enters them (that's why erase event is only temporary and why events need additional scripts to remember where they were when the map was last visited).
With multiplayer, you would have to change that to multiple map access at the same time, having all those maps run concurrently. Just think of what this would do for lag which is sometimes already a problem on a single map (and if you think that those maps run on different computers, one per player, this is only partially true - the game still needs updates from those maps to synchronise all data).
To create a RM that has networking playability even for a low number of players is big work - and Degica and Enterbrain have only limited resources to handle that.
And even if they could get it implemented (which isn't guaranteed because the base interpreter for the engine might not be fast enough to handle that, see lag on maps), the cost of the program would most likely go up quite a bit. And even if a few people are willing to pay 200$ for that, most of the target audience wouldn't be able to do that. So this implementation would also risk loosing the investment if not enough people are willing to pay for the improved program - one of the reasons XP is still around is because it's much cheaper than Ace...