Would it be possible to streamline taxes in USA? Would it not be interpreted as "making it easier to collect even more taxes"?
It depends. If you reduce the complexity of the tax system, thus reducing the required size of the tax agency, many of the same people who are anti-tax (or rather pro-lower tax) would be OK with it, because they would see that as streamlining the government.
The common idea seems to be that the tax code is very complex because there are so many add-ons to allow you pay less tax. Most US federal income tax payers can choose a simplified option, but they will not pay the minimum amount of taxes.
People, who for example think federal income tax is illegal, comprise a small enough group that they couldn't prevent simplifying the system (or any change for that matter).
A decade or so ago they decided to thoroughly sort out the tax law. Most small businesses are able to fill out their own tax (I did for years). It's about a page of information - all nicely coloured & well explained. Basically idiot proof (yes yes, I know).
Private individuals? Now things are at a point where you don't even NEED to file a tax return. Income tax is taken by your company & filed with the IRD, so unless you have extenuating circumstances, they know pretty much exactly how much you owe/are owed.
It's an absolute dream filing there, compared to anywhere else I've been.
Oh, & if you have any questions about any part of the law? They have helpful, clear pamphlets that outline all the details you need. Available over the web too. It's very cool.