"Personal preference" in large numbers determines whether a game will do well. It's just a lot of people with "personal preference." So if the majority of people prefer the dice gimmick, great, keep it. If they don't, then I guess the game won't become all that popular. Do you want it to do well or cater to a small group of peoples' "personal preference." ?
Other successful games have systems like your dice rolling system, but they usually give you a choice. Voidigo has a powerup option that basically rolls a dice to see if you'll get a very powerful weapon, but I think they have a better design because you don't have to choose to roll for that upgrade. You can just pick the standard upgrades too.
It doesn't really mean anything to "save up" for another upgrade if all upgrades are gated behind RNG. I don't know if I'll get lucky this upgrade cycle or the next. They're the same. You think it's giving players a choice, but it's taking away choice.