This was a function of many things:
-- LA did own the team he rode for, but also his performance in the TdF was so dominant, and his chances of winning so good, that it was clear USPS/DC had to follow the "tried and true" strategy of everybody riding for LA and the team focusing on the Tour. Bruyneel's strategy of having everybody ride for LA also meant that, at least prior to 2005, people knew that they shouldn't even be trying for personal achievements at the Tour such as stage wins (unless LA were to see that he had a sufficient cushion and race circumstances might permit LA to offer that prospect to a domestique, as in Landis in his last Tour with USPS).
-- Because USPS/DC was such a dominant and visible team in the peloton, many domestiques who did well supporting LA got financial lucrative offers from other teams (sometimes involving team leadership or co-leadership or the possibility thereof much faster than before LA would retire at USPS/DC). It is because precisely because USPS/DC LA domestiques get such good training and have such benefits of high visibility that they get recruited away (see Leipheimer, Landis and many others). Also, other DSs probably recognize by now that the USPS/DCs have a pretty good system for identifying talent in key lieutenants.
-- Somebody who can come along and win a Tour is not going to come along very frequently. So, it cannot be said that DC hasn't been looking. They have been trying to develop Popo, whom they tried to get onto the team several years before he actually joined. Bruyneel has very clear views of whom he tink s is talented, and I think it sometimes takes a while for them to get that person on their team. For example, Bruyneel and LA have been trying to get Savoldelli on the team for years. The Il Falco bio talks about how that rider has long been "coveted" by Bruyneel ("covet" connotes a strong and long-held desire).
-- The Indurain/Olano example is perhaps not the best one, because Olano was never as strong as Indurain. The Riis/JU example is also not too apt, because Riis didn't dominate multiple TdFs like LA and Indurain did. Also, obviously, JU's performance, while good in objective terms, can hardly be viewed as being the model of what Bruyneel is striving for.
-- Bruyneel is also suffering from the aging of some of his key TdF domestiques and stars. That was a function of his needing to keep them around to continue to support LA. But Bruyneel recruited in a way for 2006 that shows he is looking at the long run. He did not spend big money on anybody, although he did try to recruit Basso. He is building a domestique team (including climbers) to support his next young TdF contender -- likely Popo (not necessarily this year, in terms of podium, although that is possible). He already has Benjamin Noval for a person who has proven he can ride in front as rouleur and in the very early mountains for very long periods. He added Egoi Martinez as climbing support in 2006, and may be seeing whether Trent Lowe can improve his climbing. He might be able to cajole Danielson to becoming climbing support for Popo in the Tour in later years, when Danielson participates in the Tour and gets some GT experience under his belt.
I will always be around to continue to point out interesting aspects of TM's failures and DC's successes. 
