I know this is very old, but I shared recently my thoughts in a blog comment so I thought is interesting to revive the topic :
I keep seeing this opinion in the community and partly I agree with it however the issue is way more complex and from my point of view roots in distribution, pricing and partly GPL.
I started Themeisle around niche themes concept and used my SEO experience, affiliate marketing and freemium distribution to promote them, however the numbers simply doesn’t add-up.
Let’s look at Lawyeria, we have the most popular free lawyer theme in the wp repo, if you search for free lawyer wp themes we are on 2nd, if you search for best lawyer WordPress themes we are 1st in top 2 listings and added in the next ones and we are doing some adwords as well. We kind of doing maximum possible in the niche ( except themeforest/mojo ), however we sell <$1000/month, if you consider a 2-years lifetime, add commission, affiliates, marketing costs, development + support, the profit is close to 0 AND is the best performing niche theme that we have.
Considering this, we as theme developers( as well as others in the market ) can’t really invest too much development work into this, so obviously niched themes in most of the cases aren’t as good as multi-purpose ones, due to the simple fact that you CAN’T make enough money to actually invest in development.
We have some good examples in TemplateMonster / ElegantThemes, one of the biggest players which lately are focusing more and more on DIVI / Monstroid, just because is better for everybody.
If we are talking solutions, I see few :
– Increase the price for niched themes at around $199, in this way the business is sustainable
– Have TF/ W.org /mojo focusing more on niches rather than most popular kind of listings
– Use a proprietary license to better protect your work against freelancers/agencies, noways my feeling says that around 30% of paid gpl products are used for free, also this forces developers to offer unlimited sites usage kind of things at a low price.