The downside is: what if this method turns out to be not very useful and I later implement a more useful one; but meanwhile people had started depending on this behavior. Now we get into the situation where we have to maintain two methods to solve a similar problem. And worse, probably have to add yet another option to choose between them to the already long list of options that Bevel has – in some people’s opinion, too long already.
Here is the discussion the last time we discussed this issue, where I was persuaded not to do the material index method: GSoC 2018 - Bevel Improvements
This discussion has led me to think it is probably time for me to take a small break from my Boolean improvement project and fix several of the requests that keep coming up - this one, and the one for an ‘absolute leg length’ amount-mode.