I have to ask, is it really worth breaking backwards compatibility, that is, forcing an upgrade to a newer version of Perl, by adding this "feature"?
From whose perspective?
Using newer features of any version of Perl in a CPAN module means that some people won't be able to use them until they upgrade. The flip side is that some of these newer features make developing and maintaining code easier.
Volunteers are free to set that trade-off wherever they choose. The line may change over time. Even the Perl module toolchain now only targets v5.8.1, whereas it used to target v5.6 and before that v5.5.
This particular auto-dereference feature is experimental. By definition, that's the sort of thing that using in a library will reduce the number of people who try it. (It may be superseded by more recent p5p discussions about a "postfix dereference" operator. Who knows? That's why we have experiments.)
But compare that to the new s///r feature. That's something that I welcome. For some code I publish, I choose to make v5.14 a minimum because I like coding with that more than I care to support ancient perls. For other libraries, I make a different choice.
But I wouldn't hesitate to make v5.10 a minimum for just about anything general purpose these days. As others make that same decision, the days will be numbered for staying on v5.8.X and expecting the newest CPAN modules to just work.