Re: lesser threat
Not quite the same I think. Well it could be I'm not sure how browsers behave in the background when this happens. What I'm referring to is the big warning dialog that pops up saying "this cert is not trusted", and says why. Then you can override the connection if you wish (unless the site uses HSTS or whatever that thing is called) and continue connecting. I don't expect browsers to submit data until that exception is granted but they might, I haven't checked myself.
I recall back to 2004 or so time frame the company I was at had tons of SSL certs, so many that we had a special portal to Verisign's site where I could issue certs without ordering them each time and they would invoice us(something like $90,000 a year in certs). It was also my first (and probably only) experience using client side SSL certs for authentication to a website.
Anyway in one case we had a cert error that I saw, and one of the support folks wasn't seeing it. He wasn't the smartest guy in the company but he was a good support person. But he was conditioned I guess you could say to just click past SSL errors (in this case I think it was IE with a pop up dialog box one step click to bypass the error). I went to his desk and was talking him through the process to get to the error. The error popped up and he instinctively clicked the "continue" (or whatever it was called button), the error didn't even register to him. I laughed and said STOP the error was RIGHT THERE. Went back again and he realized it at that point.
So certainly people can be conditioned to go past the errors but as long as "untrusted" certs can be allowed in browsers (and if browsers some day decide to stop that I'll just, get off the internet entirely perhaps), the risk of a un trusted cert intercepting data is far greater than that of MITM decryption data because of weak(er) encryption.
But at the end of the day the whole SSL CA stuff is flawed security wise anyway since the list of CAs that are trusted seem to go on forever and there doesn't seem to be good enough controls on how certs are issued. Obviously there's been several incidents over the years where certs were issued to the "wrong" people for big domains..
But go beyond browsers, think of all of the server side applications that use SSL, I'm talking server to server communications whether it is API endpoints, email services, and other proprietary protocols that use SSL. Maintenance on SSL versions and stuff is honestly I'd call it black magic in many cases. Something as simple as the ordering of the ciphers can throw everything off.
A few months ago I upgraded some of our internal systems and when we hit production a critical external endpoint was simply failing. It worked fine prior to the upgrade, but not after. It was working in test only because they had configured it to use http. In test https would fail because the vendor's cert expired years ago so it failed validation. In production http was not allowed(on their end). After some investigation I determined they were using ciphers on their site that were now considered very insecure and OpenSSL (or gnuTLS I forget which) refused to connect to the site(no matter what). Strangely enough whichever OpenSSL or gnuTLS refused to connect the other one worked fine(so if OpenSSL was failing gnuTLS would work or vise versa I forgot which worked and which did not). I ran a SSLlabs diagnostics on the site and it was reported as a grade of "F". Ended up building an older OS system for that API call until the vendor could fix their stuff.
Fortunately for HTTPS based sites there is ssllabs testing site, without that I don't know what I'd do myself.
As for BEAST, I don't recall the details of it much, but I do recall putting an easy workaround in on my Netscaler load balancers a few years ago, back when we were prevented from upgrading the code on the load balancers to something that supported newer than TLS 1.0 due to an unrelated bug in the platform which took a good 2 years to get a resolution on.
The whole dumbing down of the internet is quite annoying to me. Present the user with choices and let them choose which they want to do (I have no problem with default choices, just let them override that if they desire). Browser vendors in particular Chrome and Firefox have been absolutely positively terrible in this regard(I say this running the Pale moon browser, I clung to firefox for as long as I could).