I take your point that its not a great place to see the Sun rise/set, mind. I think its more the "eye goddess" bit that gave it its solar name. The Sun has been connected with the eye at some stage in the history of virtually every culture.
Other nearby mounds don't seem to have a solar connection.
Merlins Mound in Marlborough is said to be the tomb of Merlin and the Hatfield Barrow inside Marden henge looked like a Hat in a Field (Only joking, it was the HeathField)
None of these mounds were usefull for solar observing.