Scout101, your concerns of treasure vs. no-treasure on Oak Island are well thought out and valid. Any mystery, historical or otherwise, needs to be examined from all angles to see if the surrounding theory holds up or not. Though I personally believe that there is treasure on Oak Island and I have my own theory as to who placed it there (and why) I also accept the fact that there are reasons to doubt that notion.
Let's examine for a moment if it's possible. In 1795, McGinnis, Vaughn and Smith managed to dig down to a depth of 30 on their own, just with the use of shovels and picks. and buckets to haul up the loose dirt. Nine years later, the Onslow Company reached a depth of 98 feet (before the water problems began), using what by our standards today would be very primitive equipment. So, is it possible that in say, 1575 or there abouts, could the original perpetrators of the Money Pit have dug that deep or further and then performed lateral tunneling to create the flood traps? I do believe that it's possible. Tin mining under the ocean has been going on in Cornwall, England for well over a century; the Crown mines have been in operation since the 1860s. The Spanish developed extensive mining techniques hundreds of years ago, so again, such a deep and extensive excavation could be done, using the technology that was available four to five centuries ago. It would just be a lot harder and take a considerably longer period of time to perform.
As to what might have been buried... My own feeling is that there was an intent to be able to retrieved it at a later time, but this is just speculation on my part. As to whether it was placed there by the Templars, while it's possible, I don't believe it to be the case. I think the folks at Prometheus Productions like to make a case for it being the Templars and the whole romantic notion of it being either the Grail or the Ark of the Covenant, and while I believe that the Templars may have come to Nova Scotia, I'm not certain it was to bury what would have already been legendary artifacts. I think that SInclair's expedition in 1398 did occur, but I'm less positive that he made landfall on Oak Island.
To address your earlier concern about there not being an endgame here, I do feel that as far as the Laginas and their business partners are concerned, there has to be one. In the decade or so since Rick and Marty purchased David Tobias' lots on the island, Marty, Craig Tester and Alan Kostrzewa have invested a lot of funding into this venture, for it to not pay off at some point. They truly have a vested interest in seeing this mystery solved, whether there is a treasure of intrinsic value there or not. Or if something is buried there, but one that is more historical in value (such as Baconian documents).
Remember: what we're seeing is what the History Channel is letting us see. As with anything, there's always more to it than what meets the eye.
BTW, if you don't mind my asking out of curiosity, how and when did you first learn of Oak Island and what about it initially sparked your interest in it?