I can settle this once and for all.......no, you do not need an MEI to get hired with an airline. I ain't got one, or even a CFII, I just speak english real good so they hired me.
Seriously, I interviewed with eagle last year without it, also, so maybe take a closer look at why you're not getting interviews(that's not meant to sound mean, I just mean that it's probably something else, maybe something that you can easliy fix).
For the new topic.....I got a 135 freight job flying twin cessnas with 100 hours of multi. It can happen...and these jobs are available with suprising frequency for guys in that position if you go where the jobs are. There are a thousand operators in the Tx, NM, AZ part of the country. I got international single-pilot 135 experience with a quality operator......that's what looks the best in my opinion, and most of the people I have met agree. Even here at the airlines.
I do enjoy reading the post way up there somewhere that said that "good personal, flying and instrument skills", I believe it was, are the things that will get you a job at the airlines.......unfortunately that aren't true. If you've got the time(or close to it) and you can fool the HR people at the interview you'll get the job......those pesky other things may help you keep it, but a lot of people slide by with only 1. Take your pick....I'm going to start putting that on my resume:
Good personal, flying, and instrument skills. (pick two)