if you are more interested in philosophical arguments, there's a fundamental asymmetry between lexicals and entries in the symbol table: lexicals always have names that are identifiers, whereas symbol table entries can have arbitrary names:
I personally believe, speaking of philosophical arguments, that having what that basically boils down to two independent variable systems is particularly annoying especially because they're in fact so similar to each other, thus adding to confusion rather than diminishing it! A posteriori, if say lexical variables looked all that different from package ones, then one would not even think of asking herself why something e.g. "works when variables are declared with our but not with my."
OTOH not only do I cherish the way Perl 6 solves the issue by implementing lexical variables as package variables thus unifying the two systems into one, "just" by means of a special, magic (and then some people still whine that Perl 6 is not magic enough any more...) package, but I... well, personally believe to even be annoying myself for having said so many times how much I would love this feature to be backported to Perl 5. Of course, if it ever were, I don't expect so in terms of an actual implementation, which would be too big a of dream but as a sort of convenient UI to modules like PadWalker & C.