I get the sense that the Daily Doubles have historically been located in the high dollar values of a category because it has been more traditional behavior for contestants to start at the top of the board and work their way down. That way, the Daily Doubles tend to get exposed later in the round, when contestants generally have more money to wager and the game situation is more likely to be swung by a big win or loss. As I understand it, the DD wager may still be made for up to the highest dollar amount on the board for the round even if the player's current score is less than that amount, but it still is undesirable from an audience point of view for the only DD of the first round to be "wasted" on the first question.
Of course, from what you might call a "power player" perspective, the Daily Double spaces are very valuable, both in terms of the potential money you can earn and in terms of denying your opponents that potential. It's smart to try and find them as soon as possible. Making the DD spaces truly random on the board may limit the use of the "harder levels first" strategy, but there's still value in building an early lead (this is assuming that as a "power player," the hard questions on Jeopardy aren't going to be substantially harder for you than the easy ones) and maintaining control of the board, so I don't think it would totally go away.