I'm personally against cast times on Bard's weaponskills. Been there done that in Heavensward, and not having it differentiates the rDPS role from the magic DPS one in gameplay. Plus, if we add cast times, then you'd be pushing out the players that enjoy the ranged gameplay without them (and there's nowhere else to go then).
That said I'm not against all cast times on it. I remember Foe's Requiem when it had a 2 second cast time. You had to pay attention a tad more to avoid pulling the boss/mobs immediately. I think songs are the perfect skills to have a cast time on (and I wouldn't mind if they were linked to MP, but those days are sadly gone).