This article keeps popping up on various geek sites over the years. In addition to the points kposehn brought up, I'll add the following: FRA isn't the reason why HSR sucks. The reason that HSR sucks is because we as a nation don't want to invest in the infrastructure to make a good HSR system. At a minimum that means exclusive ROW (grade-separated crossings) with relatively few stops and long straight sections where it can get up to speed.
As for the FTA buffering standards - it really doesn't matter. Yes, the Acela is heavier than the TGV. That extra weight isn't why Acela service sucks. The Acela is perfectly capable of maintaining 155+ mph speeds for extended periods (I witnessed this myself in Acela enduracing testing). The power cars are more than capable of handling the load - during the first few months of Acela operation, there was a problem with the network connection that linked the front and rear power cars. To get service running until the power could be sorted out, the trainsets were run with only one power car operating. Running with one power vs both power cars (and pulling the dead weight of the second power car) only increased DC to Boston run time by 5 minutes. As for cost, the price of an Acela trainset is within the range of most other popular HSR trainsets (TGV, ICE, Pendolino, etc) albiet at the higher end. The effect of the train weight on track wear is minimal as it's the unsprung mass of the train (essentially the wheels, axles, traction motors and brakes) that is proportional to wear, not the static train weight. And train weight has nothing to do with noise.
kposehn already commented on DMU but I'll add that the biggest impediment I saw to transit agencies adopting DMU's was that since no one else in the USA had them, transit agencies didn't know what to expect in terms of maintenance, operation, and environmental effects. In fact FRA and FTA were essentially begging transit agencies to try them, and it's only been recently that they've been operating in Vermont and other locations.
Finally, regarding FRA horn noise rules: first of all, the preemption of state horn rules originated with Congress who directed FRA to get involved with horn noise (Google "Swift Rail Development Act" for more information). But the reason those rules exist is because whenever there is a grade crossing fatality, inevitably the next of kin sue and all too ofter win in court. As a result, there is a tendency to do anything and everything in the name of "safety" on the part of RR operators, agencies and regulators. As long as this remains true, horns are going to be part of rail travel.
edit: btw we had this discussion at ArsTechnica back in 2008 (I'm Anechoic there as well): http://arstechnica.com/civis/viewtopic.php?p=2671067