Possibly - it certainly worked in my favour! They did build a lot of them - half a million, with over a 100,000 GT's so there are still a stack of them around which may affect prices.
Other factors are the rust issues, and I also think they have a bit of an 'old mans car' reputation - get a whole stack of people to name their top ten ' classic sports cars' and I doubt the MGB would appear in many lists.
I'm really happy with mine, and it handles its role of 'daily driver' really well, but compared to the 10 year older Mog, it's a bit of a 'poor cousin'. Did a couple of hundred miles in the Mog this weekend, and it outperforms the MG in every area (apart from comfort in the rain!)