You say you are frustrated because people don't get what you're saying but I think the fault is yours, not others. I also, contrary to what you say, don't think we're close to agreeing.

You give examples to clarify your point about future valuation but they don't help because the ones you use are useless. You keep mentioning trades that are out of balance RIGHT NOW. Your example of Smoltz and a #2 FA for Vernon Wells, Josh Phelps, A rookie #1 and a #1 FA is out of balance right now and therefore is of no use in illustrating your point. How about we use this one: After the rookie draft I trade Fred McGriff for Hee Sop Choi. Am I ripping the other owner off because "everyone knows" Choi will be great ? The experts all agree Choi will be a great power hitter for the next 10-12 years, right ? I don't think so. The other owner will win year 1 as McGriff contributes 30-ish HR's and Choi nothing. After that, who knows? Choi could be good, he could be Kevin Maas. Forget Maas, who was at least good for awhile, Choi could just plain bomb while The Crime Dog stays productive for another 2-3 years. Then I'm a big loser on this trade. Should we look back and say I shouldn't have been allowed to do it ? I don't think so, but from you've written I think you do. There are basically 4 types of trades in PB:

1) I have 2 SS, you have 2 2B's. We exchange fairly equal players. Fair and rare.
2) We exchange players who are not equal which means another item (player or pick) must be thrown into the mix. If that balances things out fine. If not, we keep adding items until it balances.
3) My team is stacked, yours has many holes. I trade you 3-4 guys who will be starters for you in exchange for 1-2 Great players. I concetrate the talent I have into a greater player at 1 position and you disperse it over 4 positions. Good for everyone.
4) Age trades. I am out of talent and therefore contention while you are a player or two from a champioship run (at least in your mind). I give up players that will definitely help you in year 1 and maybe for 2-3 years more as they decline. You give me players who have potential to be good, or picks that lead to such players. We have exchanged risks, you get more immediate aging/decline risk, I get overhyped/suck risk. Of course, I need to get more potential upside than you because if all the players involved retired tomorrow you'd still get the first years production. I, sadly, get zero. My upside is that all or most of the prospects pan out and I have a powerhouse. My downside is they all suck and I start from scratch. Your upside is the veterans help you win a championship and then stay healthy and productive for a long time, bringing more success. If we both get our upsides my players will still be All-Stars long after yours have retired. This is ok, as you were the only one gauranteed anything (the first year production) so my upside should be higher. People, and I believe you're one of them, want to have some way of valuing the future production (Fred Cline's post or your forward looking evaluation post) and not allowing this kind of trade at all.
What I'm saying is if someone here can devise a way to ascertain the future production of baseball players, young and old alike, then quit PB and go see Billy Beane. He'll hire you and you'll both get rich. It can't be done and to curtail trading because someone has the hubris to say they can see into the future is wrong.
Once again let me say, Mike allows these kinds of trades now and does a good job of it. People who want to look backwards and label a trade a 2-year old trade as unfair will, if they get their way, kill PB.