The thing is, this was the dawn of the 1990's, a time before Nirvana's Nevermind. Growing up then and living through a punk explosion.
39/Smooth cost $650 to record which bought a day or so in the studio. Music laid down in one day on a first take, the vocals the day after. GD had nowhere to hide, no studio trickery, nothing to polish or embellish the sound. The album just had the songs nothing more.
It may sound tinny and hesitant, but for me at that time I'd heard nothing like it. I still love it now every song and lyric.
As stated in the book the History of GD, "there is no band out there like GD" and "39/Smooth is as punk rock record by any estimation."
Should they have taken more time recording the album, worked on improving the sound?
I'll let Billie Joe answer that question. Speaking in Dublin in 2004 he said,
Quote: "I look back at 39/Smooth, and I honesty think that we would have fucked it up had we had more time or money to do it differently."
I love 39/Smooth & Kerplunk just as they are when they came out, my life and soul. More valuable than gold.