First of all, I completely agree with the ones who pointed out that you just don't release 4 full songs before an album comes out - whoever had the bright idea of doing so was painfully mistaken and bound to inflict damage upon the commercial outcome of the album, especially when it comes to people who may have purchased the album without being Morrissey fans.
Secondly, I do believe that the choice of promotional songs may have not been necessarily wrong at all. Considering the shockingly low musical and lyrical standards present in music nowadays (the sheer fact that people like Ed Sheeran - whom I had to google as well - can get such massive degree of critical and commercial success provokes a mix of amusement and bewilderement in me), Earth is the Loneliest Planet (since it is, by far, the lightest song on the album) could have done wonderfully well on mainstream level as a second single. Istanbul, on the other hand, seems to be a more appropriate "lettre de présentation" for the actual fans and should have been the first one to have seen the light. Of course, the fact that both songs should have had proper video backups as well, is rather evident to most people (not to whoever was in charge of the album's promotion, though).
I also believe that the choice of World Peace is None of Your Business as first single is quite erroneous, since it is neither musically/lyrically representative of the rest of the album nor does it state the obvious things in obvious ways - which is so required these days - causing confusion among potential mainstream purchasers of the album, who failed to grasp the otherwise quite obvious 1st person perspective and irony of the song. Also, I honestly fail to see why The Bullfighter Dies (which could have been the third single once the album was released) wasn't prolonged to 3 minutes at least, having the necessary space and the right potential for this to have been done.
Finally, it's up to Morrissey the fact that he could have actually pulled out greater lyrics, as well as set out to improve the timing and rhymes on many songs. Being this a musically great album, I fail to see why Morrissey did not put more effort into the lyrics - it's OK if you keep things simple deliberately, as it's the case of Earth is the Loneliest Planet, but otherwise it is perceived the way it is: lazy songwriting (on lyrical level only, of course).
In any case, I do keep fingers crossed for World Peace to attain yet another #1 for Morrissey for 4 consecutive decades indeed.