Mostly flavor, but some mechanical. You won't be casting wish in combat any more.

From the Ritual entry on AON (emphasis mine to highlight the changes from Wish as a spell):

A ritual is an esoteric and complex spell that anyone can cast. It takes much longer to cast a ritual than a normal spell, but rituals can have more powerful effects.

When you take charge of a ritual, you are its primary caster, and others assisting you are secondary casters. You can be a primary caster for a ritual even if you can’t cast spells. You must know the ritual, and the ritual’s spell level can be no higher than half your level rounded up. You must also have the required proficiency rank in the skill used for the ritual’s primary check (see Checks below), and as the primary caster, you must attempt this skill check to determine the ritual’s effects. The primary skill check determines the tradition. Rituals do not require spell slots to cast. You can heighten a ritual up to half your level rounded up, decided when the ritual is initiated. A ritual always takes at least 1 hour to perform, and often longer. While a ritual is a downtime activity, it’s possible—albeit risky—to perform a ritual during exploration with enough uninterrupted time. A ritual’s casting time is usually listed in days. Each day of casting requires 8 hours of participation in the ritual from all casters, with breaks during multiday rituals to allow rest. One caster can continue a multiday ritual, usually with some light chanting or meditation, while the other casters rest. All rituals require material, somatic, and verbal components throughout their casting time.

Considering that Wish is supposed to be the end-all-be-all of spells, it makes sense that it would be a ritual rather than just a quick "wave my hands and say mumbo jumbo" cast as an afterthought. It now takes at least an hour, requires gathering other spell casters, multiple checks, and it fits the description of a ritual in that it can have more powerful effects than a normal spell.

Edit to add: I may have misunderstood your question. The adjustment I was referring too was the change from a spell to a ritual, not that rituals had been adjusted.