IMHO, why LI is so succesfull and everybody use it so much? Because it's easy to use. It relies solely on IS of the two big men plus a SF that's actually another PF with much more OD.
Why R&G isn't used as much as LI? Because you have to rely on JS... and JR... and Driving. That's a 3-skill set.
Yeah Driving is useful also for big men, but they don't need high levels since is considered more an "outside set" skill, so it's effective even at low levels for them.
A solution? Delete that crappy skill called "shot blocking", who needs 20 levels of that s***? Replace it with a "limitator skil" like, let's say, "Low post" or "Post moves"... in this way, you'll need at least 2 skills for using Inside Tactics effectively. Combine this with the necessity of having a good Ball Movement and you'll have a fairer set of tactics.
I honestly think this isn't related to a "broken" 2-3 or due to a "overwhelming" LI. In my opinion this is about popular knowledge and player availability.
Most managers already do know how to play an inside offense and it's pretty easy to find players in the market to do it. But we don't have the same experiencia with neutral or outside offenses plus it's not easy to players to run them.
A untested hyphotesis could be that player availability it's strongly related to the needs of training of every team and if most teams know how to make a succesful inside offense they are going to train players for it, some of them will be sold and some of them will reamin within the team. If you already have inside offense oriented players in your team, you have a "strategic commitment" with the inside offense. This means that it's harder to change to another offense than to continue specializing in LI. But, since managers are not stupid, they have seen the value of being able to play more tactics. And what we have seen it's an effort to build a "two offenses" teams, but always having in mind the strategic commitment already made to inside focus. This two-offenses teams are able to run inside or outside focus but the inside one is always the strongest, therefore, it's most played in harder games like B3.
The issue is that new teams and followers managers look at how are playing top managers and continue to see LI as the dominant effort, and since player availability is dominated by the training patters of mayority(non-top managers), everything reinforces LI. That's why we don't see 15-19-17 C's and we find tons of 19-17-15 C's. Same phenomenon occurs when looking player availability for guards and SF's. This makes even harder to switch to another offenses.