I think that the Rulebreaker mechanic makes sense as a solution for a problem that WotC had to contend with. Mystery Booster is a draft oriented product, which means that a player is going to be subject to random chance in regards to what cards they have available to them. There is also going to be some indecision at the start as to what direction and colours the player is going to want to go with. The issue that all leads to is that sometimes a player can't find a commander card suitable for the cards that they have drafted. Mono-colour is theoretically the safest way to draft but depending on how the draft goes that's not always possible. Or you might start with a commander early and start drafting its colours only for those colours to dry up on you later in the draft, resulting in a poor deck. Having commanders that are flexible enough to accommodate different colour combinations makes the issue easier to handle, and the Rulebreaker mechanic offers that in exchange for drafting around a theme. It's a reasonable solution to the problem.

When WotC last did a similar product (Commander Legends) they addressed the issue by having a bunch of legendary cards with the Partner mechanic, which is honestly just as much of a break from the typical rules of commander as Rulebreaker is. The more Partner cards that WotC prints, the higher the chance that they end up printing cards that make broken combinations, so I'm glad that they tried something different with Rulebreaker. Rograkh, Son of Rohgahh looks pretty unoffensive at first glance but it went on to have a big impact in cEDH because it provided a free first turn resource that let cards like Fierce GuardianshipGC be cast for free turn 1. It is also free sac fodder for a turn 1 Culling the Weak for a quick mana boost. The less unintended accidents like that, the happier I am.