If you are trying for a Wallflowers feel, or any contemporary music (which the Wallflowers are honestly a little past their shelf life, anyway!), you've got to concentrate a LOT more about just the basic chord and melody structure. It's not simply a matter of STYLE...

What I would suggest is to go out, and buy two or three CD's by bands currently successful. Now chart each song, Nashville out the chords, and write the melody... Look for how simple things tend to be. Look for how little complexity in the changes there is. Look for how often sections repeat whole chord structures from other parts of the song. Look at the melody, and see how relatively un-virtuostic it is...

That's the sound of modern pop. It is generally a far cry from the typical chordal complexity in music from the sixties and seventies, and the vocal stylings and range are completely different.

Look at how fast the hook arrives. You seldom get the length of setup for the hook as you used to. Sometimes, there IS no hook, just a change of guitar tone!

You've also got to understand that, except possibly in Nashville, there really isn't the market for selling songs to publishing houses any more. Bands write their own material, on the whole, or work with songwriters they are familiar with. Ever since the Beatles, bands have realized that the majority of the money to be made doesn't come from selling a few records. It comes from owning the songs themselves.
Once upon a time, the job of the A&R man was to put Artists and Repertoire together, pick the songs that suited the band or singer. Now their job is to go out and find artists that are usually writing their own stuff, and get them signed with as little input as possible...

Maybe a different avenue than simply submitting songs to publishing houses is to go out and find good local bands that might be receptive to your writing, and see if THEY want to use your songs. In other words, bypass the publishing house. If they get signed, you'll get the deal... But perhaps working with young musicians that NEED material might get you into writing songs in the style of modern bands. I'm afraid it's a kind of uphill battle tying to sell something as dated as this is (no offense, just describing the genre).

But there's a LOT about your writing style that naturally reflects what you are most interested in. Unfortunately, the time to write those songs was back in the seventies, when that WAS the style. Immerse yourself in what is NOW, steep yourself in the chordal vocabulary that is being spoken NOW, the melody styles that are being used, and you vastly increase your chance of success.

Trying to shoehorn a modern arranger style on dated chords and melody won't help at all, IMO. It's got little to do with the production (publishing houses won't give a damn about the production), and everything to do with the song...