why it's good not to 'niche'

There seems to be an 'accepted wisdom', lots of encouragement, and direction for us as freelancers, sole traders, and micro enterprises, and other types of businesses, to 'niche' - focus on one specialist thing and be the best at offering that. The logic we're given for this is that it will help make us more successful because:

1. it's then quicker and easier to explain what it is you do, and so be able to establish your brand, profile, etc with less effort;
2. it's easier to build a 'higher value' offer (i.e. make more money with less effort);
3. (and probably lots of other things that I forget, because I don't actually like the idea of 'niching' as you're about to learn, so I tend to block out the rest...)

BUT...

I don't 'niche' in what I offer as a business, and I'm not sure what circumstances might have to transpire for me to want to. That's because for me, the risks associating with niching are more than 'blown out of the water' by the benefits of my remaining a 'generalist':

1. Focusing on one thing means I wouldn't be using the full scope of the skill set that I've developed and identified I have over these last 20 years. Niching for me would me killing off parts of who I am and what I can do that might otherwise be interesting, useful, and fun.
2. I have an idea that niching ultimately offers less value to the clients, groups, and people I work with. Being a one-trick pony, however world-shatteringly good I'd be at it, would mean that I can't cross connect ideas and support from other themes and topics for them, to enhance the overall impact of my support to them (which would ultimately leave them poorer from the experience of my having walked alongside them for a time, than they are now).
3. Financially, niching is very risky. While it's true that the more niche you are, then the more likelihood you'd have of being able to have higher charge; the ultra-specialism of your focus and offer would mean that there are fewer potential overall clients who'd want or need your support. And they'd all be in largely the same place - which roughly means that all your eggs are in a single basket (or jars of tahini if you're a vegan), or who are all in same boat. If there's a recession, a shift in market trends, changes legislation or policy, etc, then you may find your market disappears overnight, with nowhere to easily turn to keep yourself going.

Reflecting on all of the above, I'm left wondering of niching is ultimately a 'cop out' for people who don't want to stretch themselves in building their skills as to what they might offer clients. Or if not, that they represent a group of people who are far happier and more comfortable to take risks than me?

If the former, then it's another example of how so many businesses are accepting the guidance they're offered at face value without questioning it, even if it means it's ultimately increasing the risk that they're fail in the future? If it's the latter, then I'm OK with being a relative scaredy-cat in comparison to them.