scale rather than concept. That said, Valkyrie style designs are at the far, far end of practical theory and again are more proof of concept ideas that big as interstellar distances are they're not insurmountable. And that can be important to keep in mind in these discussions because the line between impossible/improbable/impractical gets blurred very quickly.
|A common answer postulated by one of the authors is the Icarus array, many near-sol solar arrays beaming power to the rest of the solarsystem. Again it's a matter of scale and infrastructure but we could capture vastly more of the suns energy than we already do, and we can do so without resorting to magitek wormhole siphons or the like.|
As for the why - well, you're right, Silveroak, profitable return will be hard but the resources of the Solar System are finite; if we're talking long term species survival type future at some point humanity has to expand beyond the solar system. That point may be so far off as to seem hypothetical but it's there, all the same.