The thing is PvP modes are generally seen more apprehensive for a lot of people to start. I think the people who are saying rewards won't matter because people should PvP because they like to PvP are underestimating the benefit of getting people to try it. Heck, while I loved PvP in more skill-bases MMORPGs I never wanted to try it in FFXIV because tab target MMOs are relatively shallow and very poorly indexed towards ability (compared to, say, fighting games). It was only the constant addition of exclusive things that got me to try it, and by requiring prolonged play I gave it a genuine chance. I was able to accept that while it's not the best PvP game, it's still a lot of fun.

FFXIV is a fundamentally PvE game. When you start you are dropped into PvE. Most of the experiences are PvE. You can't even PvP from the get-go if you wanted to. It's not really reasonable to try to analogize that people who want to PvP are already PvPing. People often don't know what they wanted until they get it, or it's exposed to them, and a lot of people are going to become those who can enjoy PvP as a side activity in addition to PvE. IMO casual PvPers should be welcomed and the goofy, random, volatile gameplay of frontlines is the most casual, least competitive, and relaxed gateway to try to coax them into trying it.

I also don't think it's fair to say people who like PvP will PvP without rewards. Someone like myself these days? Yeah I have long since gotten everything I could from wolf marks and tomestones but I keep PvPing because it's fun, but gamers in general like external motivators, not unlike those in PvE would run less dungeons if they didn't get some kind of virtual reward for it. It's hard to quantify if what PvP already had was gripping enough to pull people in, and timed rewards could be just that little bit to get someone to reconsider.