Spot on. In order to increase the user base of Hive, you have to show that there are good apps worth using. You mentioned Splinterlands as one example. Games are a good way to do that. Another game that is doing well is Rising Star. Gaming is only one avenue to attract new users to Hive, and new developers willing to invest their time, money, and talent to build applications.
But games are not, nor should be, the only types of applications to interest people. Actifit is another app that could be a good way to attract more people to engage in the Hive ecosystem.
Then there is the blogging space on Hive, with lots of communities, many of which have a good user base, and there again, there is opportunity to leverage the blogging community to attract more users to the Hive ecosystem, and in this case, Hive Community. LeoFinance is one example, along with CineTV, various games on Hive are building communities. And there are communities for artists, photographers, poets, and so on as well, some have their own token on the Hive.
Developers will come to Hive (or other crypto blockchains) if they think the application they build will attract enough users to justify the expense in building, supporting and improving the app. Some games may be free to play, but at the end of the day, developers want to be able to have a roof over their head and food on the table (and maybe a couple of beers).
My two cents, for what their worth.