I deliberately chose the smallest, easiest syntax change which represented a useful feature, and the negative responses have been:

• You can't add syntax to Perl 5. (Fine, now you have to use the feature pragma to enable it.)
• It might break existing code which defines a class method featured in an indirect call on a bareword which passes a hash reference as its argument. (See the previous point.)
• I don't understand how it's useful. (Fine, don't use it. I don't understand how the Perl 4-style package separator is still useful fourteen years, two months, and three days after the first release of Perl 5 which used a much better package separator.)
• It doesn't do enough. (I thought small patches were easier to review, and I'm not interested in wasting my time writing a complete replacement of Perl 5's object system if I can't even get a simple dumb patch like this accepted.)
• Moose hackers reserve the right to modify syntax and features to explore alternate approaches, and reportedly don't want old code to go stale in the core, if the Perl 5 release policy remains as it is. (Of course, I've only heard this secondhand and probably shouldn't include it in the list, but it is an objection I've heard. Remember though, that my patch represents the Perl 6 syntax which has remained stable for longer than Moose has existed. I helped design the Perl 6 object system.)
• I prefer the existing syntax. (Then don't use it. It's optional. If you adamantly oppose adding new features to make a language easier to learn and to use, boy do you have the wrong language.)
• You can already get the same syntax with a source filter, a CPAN module, a minilanguage written by hijacking and copying parts of Perl 5's tokenizer into an XS module. (Clearly this is a problem many people have wanted to solve. What's so bad about solving part of it once and for all for everyone?)

It's no surprise there's a lack of volunteers lining up to add and maintain features for Perl 5. I'm motivated or stupid or gullible or stubborn enough to have patched Perl 5's parser and lexer twice this year. I don't mind doing hard work, but I'm not motivated or stupid or gullible or stubborn enough to waste my time if there's no chance my work will ever be used.

Update: Rephrased the Moose comment to reflect reality more clearly.