This quote from Alexander Knight...
... seems to suggest to me that there may have been motivation to not incentive mass industrialization as a strategy.
That said, there are benefits to upgrading worlds. More options for placing new Combat Commands and better garrisons.
Edited for clarity:
By weakening the value of industrialization, you haven't really prevented mass industrialization as a strategy. The reason for that is that mass industrialization is not the point. The point is the strategy of RP investment. Investing RP in factories is just one way of investing RP. The best way of investing RP is already a 5% return, so weakening industrialization doesn't actually lower the rate of return on RP. Weakening industrialization accomplishes nothing. Banking RP is still viable, and the game says the basic interest rate for banking RP is 5%. It offers an alternative savings vehicle (Minor -> Major Industrialization) that provides 1.7%. No-one will use that alternative investment vehicle, because its returns are poor. It might as well not exist.
Improving the return of this investment vehicle will make mass industrialization more viable, but as long as you keep it in the ballpark of 5% interest, you won't see it taking off suddenly.
If you're worried about mass industrialization as a tactic in ISW, what you should really be asking is whether the 5% interest rate on unspent RP is too high. Will we see people banking vast pools of unspent RP in some nebulous carried-over balance?