OK, 150 atmospheres pressure - maybe, and when the gloss has worn off and the process starts to seem a bit humdrum, will everybody involved still remain constantly vigilant and careful and not succumb to the temptation to cut corners? We know the answer to that.
But are you seriously saying that you want to risk lives and huge investments by having people working in bottles at 400 atm of pressure which is what you get 4km down where many of the spreading centres are located? Are you volunteering?
I think a comparison with the NASA space shuttle program is apposite: apparently the fine print of the project definition settled for something like a 0.1% failure rate, and that seems to have been quite accurate. With spectacular results: 2 hulls lost with all aboard each time.
Now it seems to me that if the engineers and their bean counting masters had built the airframes with titanium instead of aluminium in the important places at least one of those disasters would have been mitigated.