Because people did do the exact same thing before, and it turned out to be rife with fraud. That's why the regulations were put in place.
"so you're really just calling for ICO-like fundraising to be banned."
No, they're just calling for it to be called what it is: A Security.
Not all of them have been, however. Ethereum was arguably not a security. It's not necessarily a security offering if you are putting something up for sale that has a value of its own, or will have a value when the transaction occurs, such that people buying the thing are not expecting to get anything like a "return on investment", and are not expecting to somehow profit from the work of the company who is making the sale.
Consider Kickstarter-style presales: the people who buy these offerings are buying a product, not investing in the company. If you were, for example, just selling a token where the token has some intrinsic value (such as enabling you to pay for distributed compute or storage), and where you're clear to buyers that there's no expectation of any kind of return, just the token's intrinsic value, then that's probably not a security.
I believe I also read that there are requirements that the thing-you're-buying have value at the time the transaction takes place, though I'm less sure about this. If you take presales for a token that doesn't even exist yet, with a plan to fund actual development of the token off the presale funds, then that may be a security. If the token that you sell has value at the time you sell it, or will have value at the time the transaction takes place, then that's probably not a security.
If you read the Ethereum project's presale materials, they were very careful to stay within all of these boundaries, from what I can discern. This is my layman's analysis of securities law - IANAL.
That is a feature, not a flaw.
It is a flaw for those banned from being recognized as "accredited investors".
It is a feature for those lucky to have competition banned.
One is to say that the government want to protect people against themselves, to make sure they can withstand significant financial losses.
Another explanation is that those who match these conditions (I'd guess about 2% of the population) have successfully lobbied the government to maintain their advantage against the remaining 98%.
I do not understand why people downvote when I just say out loud the less palatable alternatives views. It seems to me we are not considering all the possibilities there.
Ultimately, SEC regulations don't allow people to do what they want to do (and I don't think the limitations of SAFTs/TCOs have become obvious yet), so you're really just calling for ICO-like fundraising to be banned. That would be fine with me, but don't expect people who raised millions to just give that money back with no resistance.