I don’t know if it would have been a wise choice, or IC for Damon. Yes, you can consider him a womanizer if you want, he clearly loves the ladies.
But both what he felt for Katherine and what he now feels for Elena… I think it proves that Damon falls in love rarely. He’s very much the type that when he falls for you, it’s forever.
Think about his love/obsession for Katherine for 145 years. And even after knowing that she lied to him about her “death”, he was ready to give her and them a second chance. I think the combination of knowing the truth (that she never loved him - Katherine told that to him in 2x01) and meeting and successively falling for Elena is what helped him move on.
He’s always “extreme” in the way he loves. For him, it’s that person, and nobody else matters. Think about how much he’s in love with Elena. How he always puts her first. He would do anything for her. And even when rejected, he stayed.
Damon is the type that wants the eternity with the one for him. If any of his “relationship”/hook-ups had been explored, it would have been a lie. I don’t think he’s the type that can have a relationship when in love with someone else. Or the type that could fall for somone else while he was clearly in love with Elena.
For 145 years he didn’t move on from Katherine until he met Elena (and he was rejected by Katherine). From what we know both now and over the 145 years as a vampire he only had hook ups, nothing really serious.
It’s just the type of person that Damon is. Exploring a relationship with someone he wasn’t in love with… I think it would have been pointless.
What I think it could have been explored was a friendship for Damon. Yes, before anything happened with Elena, they were friends. But what I would have liked to see was for example a friendship with Rose (she didn’t last that much). Even without anything physical, I think it would have been cute for Damon to have a female friend like Rose. I love Dalaric, I love them so much, but I think a female friendship for Damon would be sweet to see.