That's a fair point and one of the biggest criticisms of intent playing into the canons so prominently - but the entire American legal system is built on precedent and tradition.So that begs the question: Is there really any legislative intent involved in the passage of laws anymore? If legislation is largely crafted by non-legislators and legislators generally don't know the details of the bills they are considering (reference Nancy Pelosi here), then the legal principle of "legislative intent" seems obsolete and plain reading of the text seems to be the most reliable principle of construction in my opinion.
By the way, how many lawyers are employed by the offices of legal counsel for the Senate and the House?
Which takes me to another thing I find funny that few Americans know and those in the know (e.g., TV talking heads) pretend they don't:
Much of those speeches you see made on the floor of Congress and the questions and comments they make during a Congressional hearing are written by special interests.
To correct what some have said, it is not the lobbyists themselves actually writing all this stuff. They are merely the vehicle.
The Office of Legislative Counsel has many lawyers in their employ, all of which are overworked and underpaid for the garbage they have to deal with on a daily basis.