Because Boeing has hung us out to dry after decades of supporting their company buying their 60 yr old steampunk POS. There should have been a guppy replacement on the market 10 yrs ago, no matter what SWA beancounters told them. And just this year Boeing told the world that the 737 replacement is on indefinite hold. I don't think SWA needs any more small airplanes either, but there doesn't seem to be many options. A220-300s and A321NEO would be an "upgrade" from the switch forest steampunk nightmare we're currently flying, but the real answer is a completely new design optimized for 140-230 pax, not a tiny airplane that maxes out around 140 and absolutely nothing above that other than a shorty 787.

Boeing and Airbus have both completely abandoned the 140-200 pax NB market, because the MAX and 320 family continue to sell in spite of being hopelessly obsolete. A4A ought to do what they're supposed to be doing for the industry as a whole, leaning on both Airbus and Boeing to come up with a guppy and 320 replacement sooner rather than later.

Also A4A should be leaning on the president to fix KCM but that's another rant entirely...