Well, the issue is that you're advocating siphoning off most of the "Interesting" job design to make the fluff "Limited" version of the job.
So, instead of creating 1 coherent class with an interesting set of mechanics you're making 1 Limited Job with an interesting set of mechanics and one "Standard" class.
Which is difficult to do properly, especially if you're trying to make the "2" jobs unique rather than effectively just making 1 job that can adapt to "Fun" content or "Balanced" content.
It would only be boring when they're doing this half measure of designing BLU where they want to have many spells but don't want to make clear favourites.
To say nothing about the incredible flexibility this would give for adding spells into the "Fun" category as everything that isn't a "Recolour" of the "Balanced" kit can be OP as it would inherently be unusable in any content where balance matters.
Also, just calling them "Recolour" skills is not quite accurate, since there's plenty of room for significant differences between skills - More than the current "Everything is a 130 potency skill just with different AoE's"
Such as more combo interaction (Rebalanced with some form of non-CC based element synergy akin to something I've suggested previously)
Or creating some differences between skills that are situational (Such as a skill like Drill Cannon being a 125 potency skill that is better than a 130 potency skill when there's a DRG for Piercing debuff)
There's a lot that can be done while still keeping within a more focused design of a "Balanced Skill Set" with potential skill swaps that are limited to certain skills and action types (I.e. 130ish potency filler skill. DoT skill. 30s oGCD, 60s oGCD, 90s oGCD etc)
Simple is good. Simple costs less time and resources. Simple makes sense.
I also don't think that BLU is so out of whack that it needs to be recreated from scratch. Twice.
I think that the existing framework for can be easily moulded into a job that has both the aspects of being a fun side-job to mess around with in old content using silly abilities as well as being a functional job that can be balanced in regular content.