I've thought about it myself but SEPTA seems to have an aversion against short railroad routes. Also, a trail is destined for THAT right-of-way too. Plus, the distance between 309 at that branch and the main line is what, 3/4 of a mile? It's role as a draw off of 309 from the north is largely satisfied by Fort Washington.
I think the ire comes from the fact that it was that service was suspended by SEPTA and is SEPTA owned. The Fort Washington branch was abandoned by the Pennsylvania Railroad in 1954 and the ROW up to 309 is owned by PECO.
I understand the sentiment though. The DVARP report from 1973 posted in another topic really illustrates how much then-clear right-of-way has been lost, such as West Chester to Frazier, the Oxford Road (would have made for a hell of a light rail route), Fairhill, K&T and Tacony Branches, Plymouth Branch, Schyullkill Branch west of Norristown, Chester Valley (especially the section abandoned in 2011!), the Bel Del (in conjunction with a connection to the WT and Trenton branches would have made for a fair joint SEPTA/NJT service with stations at river crossings), Newtown Square, etc, etc.