For ease of continued trips east and regional connectivity benefits, yes there is a advantage - in fact,
Metrolinx tested a few options in the early 2010s as part of the Planning process - including a continuous LRT to Don Mills, LRT to Shepard-Yonge, extension of the subway to (then) Downsview etc.
View attachment 318040
However, the
Environmental Assessment (links down the page) for the line has the line as far as Yonge St (Finch Station) - much easier to build this "approved" line.
Any other extension options east such as a LRT extension to Sheppard-Yonge, or a subway extension to Sheppard West (don't be surprised if some councillors try to push that instead
) would require an EA.