Dịch - Romanian-Spanish - Sunt un zâmbet pierdut...

Opino que, sin el pronombre, suena un tanto más romántico, como nos pide Dulcineea.

comparto plenamente tu opinión. Gracias!

I'd add that it depends on the language, as for French it wouldn't. It would be more confusing, also maybe more poetic, but if in Spanish or Romanian a verb can well be going without a pronoun, here with this particular verb in French there would be an ambiguity (that also would lead into a poetic register, that's also true, but...) as "suis" is also a conjugated form used with another verb ("suivre", at second person singular of the imperative) the meaning would be different then.

I entirely agree with you, Francky! I was referring only to Spanish and Catalan.