My take is that the party at the end is the last time we see all our friends and the original set up works fine if you keep the party.

He burns the last of Vader and at the party Luke has bitter sweet feelings because even though the Rebels have won the war, his mentors aren't there.

Then Ben and Yoda turn up and finally his Dad as the icing on the cake.

It completes Luke's journey.

If you take out the party and the galactic celebrations introduced in 1997 and 2004 then you can just end with the fire and Luke looking up into space and the credits.

Having Anakin on his own doesn't really work because though he was Luke's biological Father, he was raised by Owen and illumined by Ben and Yoda.

So Luke's dad is really a sort of trinity (seeing as Owen can't come back as a ghost).