Sorry, I can't really offer an answer, but I did notice the same thing. I have been away from the aquarium hobby for several years. I am just now getting back in, and was rather shocked when I walked into Pet Land, and found the aquatic department so small. Also, I did hear the same thing from one of the employees when I was in there, that she was brand new. They have been running adds in the paper looking to hire more people. Maybe they had some kind of management turnover.
I was never a huge fan of Pet Land. It seems they really varied in quality from store to store. However, it was a lot better resource then what we have now in Tyler, which is nothing. There is a new aquarium store off of 110 almost to Whitehouse, but it has a saltwater focus. I guess Dallas is really the closest place to Tyler to find anything decent. Maybe Shreveport has something. I will have to check into that.
Side note I was kind of surprised that PetCo has increased its offering of planted tank supplies when I checked them out recently. They had a few cheap CO2 system knock offs similar to the Fluval 88. I think the brand name was Ista. They also had some Eco Complete, and Flourite. Along with some other supply type items. I'm no fan of the big retailers, but it was a lot more then they used to carry, which was nothing. Of course its been 6-7 years since I had a planted tank.