This is the case with every single player that ever hits free agency. By the time a guy becomes a free agent at the likely age of 29-31, if he was a star, he will command a contract that will likely have a poor back-end of the deal. If you think it's great to walk away from a long-term contract at age 29, then you're basically against ever signing any elite free agents. That's fine of course, that basically makes you operate like the Rays, but that strategy will not work for every team the way it does the Rays.
Again, an opt-out in this particular deal is not good. The argument of having a bad back-end of the deal works for guys that have contracts that end at 37 years old. In this particular situation, a straight seven year contract (age 25-32) is more valuable than a seven year contract with an opt-out after 4 years. In both situations, if the player sucked, you're stuck for seven years, but since players don't generally fall off cliffs from 29-32, in the event that the player turned out to be a superstar, you get only four market value/below market value years, as opposed to seven. At that point, yes, you can walk away, or you can choose to renegotiate, but those are still three good years that the payer had in his contract that you will not receive.
Opt outs basically just tell the player "If you're s***, we'll continue to pay you, but if you're good, you can leave". They almost never make sense.