I think what non-destiel shippers / antihellers don't understand about shipping destiel is that they think it's about having two guys together on screen. Which I mean, that's awesome, don't get me wrong, queer rep is important. But more importantly, I feel like Dean Winchester deserves to have someone who loves him and takes care of him and wants him in a way that no one else ever has. And while obviously he loved Lisa, and Lisa loved him back, it's not the same because Lisa could never understand him and know him (for all the good and all the bad) in the same way that Cas does.
You could say that this doesn't necessarily have to be a romantic love, but goddamn it, doesn't he deserve that? Deserved to be loved? Are you telling me that Sam gets to have a wife and a kid when he's in Heaven but Dean doesn't get to have someone like that? Dean never got to meet someone and fall in love again like Sam did. Is Dean just supposed to meet someone in Heaven? Could he even meet someone in Heaven who would understand and love him the way Cas does?
A lot of people I've talked to are usually split between believing that Dean either reciprocates Cas' feelings or he doesn't, and people will try to provide proof either way. But honestly, while I personally do believe Dean reciprocates, it could go either way depending on how the story is written. What I honestly think the most is that I hope he does. I hope he loves Cas back because Cas is his one chance at finding that happiness, especially after his life was cut short. I hope that he gets to spend his days with the person he loves because he deserves it! I hope that he finally gets to love fully and be fully loved in return for the first time.