The issue with Roy is how he's a one-done Fire Emblem character who got into Melee due to promotional reasons and being a quick clone.
When we have a different clone of that same character who got rushed in due to popularity and promotion, many people feel like Roy should not have been a priority for DLC weither it be pre or post ballot.
The fact that FE is a series that some were upset about having 4 characters does not help him gain any open arms as a 5th.
And, in comparison, veterans such as
and... despite their issues,
&
have comparable or more fan demand and certainly more uniqueness to their moveset.