IME as someone who does freelance work in the UK, the tax treatment usually isn't a big win. There are some tax advantages, but in practice they are usually balanced or significantly outweighed by the extra overheads of running a business (accounting, legal, insurance, equipment purchases, etc.), the loss of typical employee benefits (paid time off, pension contributions, etc.), and the risk of downtime when you don't have work. If these kinds of downsides don't apply to you, then you're likely to be treated as a disguised employee and the IR35 rules will negate the tax advantages as well.

I find the big difference in moving to contract/freelance work in the UK is that you change the frame of reference from employer-employee negotiations and their associated expectations to business-business negotiations and their very different associated expectations. If you're good, and therefore generate a lot of obvious value to clients, the latter removes the glass ceiling. I suspect not coincidentally, as you mentioned, rates for this kind of work seem to be much more consistent among different countries.

Step 1. Remove nag message. Step 2. Release to the world. Day 3. Tonnes of people jump to non-nag version and never pay.

The plugin system and API is available for those that wish to complement or extend the editor. Making the code available directly harms their ability to make money and their ability to continue to invest time and money building the product.