For those who watched DS9 during its first airings, did it seem odd to you that Vic Fontaine/James Darren sang entire songs in the later seasons of DS9?

I only finished watching DS9 recently and just found it really odd. It seems out of place in the regular TNG/DS9 format, didn't drove the plotline forward, and sometimes felt just like a filler.

(I don't mean to be disrespectful, I like the character and the actor can sing well, I am just curious why the producers made that decision).