They have several key benefits the first of which is the space that they take up or rather lack of it. Indeed one of the main benefits of a multi-games table is the fact that rather than having thirty four different boxes, as an example, you just have one slightly larger box that contains all of the games within it. To access the games you simply lift off the different boards and put the one that you want on the top of the table in order to play it. Some of the simpler ones that just contain two games will have a board that simply flips over to reveal another game or two on the other side of the board.
Some of the most popular games are the four in one tables. Typically these will contain table football, ping pong, snooker and pool, as these are the most popular out of the larger scale games. Whilst obviously these types of tables do not offer the full scale experience of a 6 foot pool table as an example, they do offer very playable mini-versions of the games. In an average household this can actually be an advantage as when playing ping pong on a smaller table you can have enough room to move around to easily play and have a good game. Where as a large full-size ping pong table would be just about unplayable in an average size living room.
The compact size of the multi-games tables also means that they are easily stored in your garage or attic, the same cannot be said about a full-size snooker table or table tennis table, both of which tend to require a dedicated room to put them in.
Lastly is the cost benefit that they bring, as they are far cheaper to purchase than if you were to buy all of the games contained within them individually.