It's just a stupid meme at this point, which came about I believe due to comments Yoshi and the development team made over the years that players either mistranslated entirelly or just took out of context (the basic idea is that ARR "uses 1.0 code" which "prevents <insert desired/requested addition/content/improvement here> from being implemented. It doesn't use 1.0 code or 1.0's engine at all, something Yoshi actually came out and stated officially).

Many of the limitations of the game are by design and were simply done to expidiate development and get the game's client and servers running stably and efficently (by comparison with 1.0), but by doing so they had to make it a 'closed system' that is very hard to expand on it's core functions (glamour being an example of this).

And as Larirawiel said, when you get down to it, all computer code is by it's very nature 'spaghetti code' - rare is the program that is designed simply and efficently and expanding on requirements places extra strain and complexity to it, it's the nature of the beast.