Uh... there's a bit of confusion there at the end. Indeed, games normally use pseudo-random number generators, and for good reason! Those can be made to yield predictable sequences, which is vital for testing. But it doesn't mean roguelikes are random: try plopping down wall tiles at random on an empty map and see how well it works. No, roguelikes are procedural, which is not the same thing. They use randomness as a tool: just one input into the process.
And text adventures are hard because you need a lot of content to flesh them out. Much more than new authors expect or realize. Doubly so if their writing experience is limited. Then you have the expectations of publishers and/or audiences, that inflate the numbers even more.