Lots of misinformation about Roy in this topic.
First off the so-called FE fans that don't like Roy are a niche of Western FE fans that don't like lords who are not able to solo everything on the map. Due to Roy's absurdly late promotion period, he can't gain more experience by mid-game, which cripples his performance as an unit. In terms of Western FE fans who have played the Japanese games, FE6 typically ranks as the second-most popular of the Japan-only titles. The only Japan-only FE title to be more highly regarded is FE4.
As for Japanese FE fans, Roy ranks as among the most popular of the FE lords. FE6 in general is among the most popular installments there. The most popular installments are FE3, FE4, FE6, and FE7. Surprisingly, while FE13 was well-received in Japan, there is some divisiveness about the game amongst Japanese fans, particularly amongst some feeling some of the characters designs and fanservice were inappropriate for Fire Emblem and the dumbing down of map design and story.
Roy in general has always been amongst the most popular Smash Bros. characters, especially clones. Even in the West, I have seen Roy rank among the Top 10 most wanted DLC choices. In Japan though, Roy probably ranks as the most popular DLC choice, if not then in the Top 3. Roy, and Mewtwo, were the most wanted characters for Smash 4 among Japanese fans, and Roy himself was in the Top 10 most wanted characters in the West.
Roy haters have been spewing lies for years, but now their chickens are coming home to roost. The fact is that lots of people enjoyed Roy, and it was his inclusion, along with Marth's, that helped many people get into Fire Emblem in the first place. I'm sure most people who love Lucas, Ness, Marth, Ike, Captain Falcon, ROB, and Ice Climbers have not played their source material, but that doesn't make them any less legitimate fans of the character.
So stay salty misinformation spreaders.