The defending driver should have the right to pick his line, and then should stick to it, absolutely.
It then becomes the responsibility of the overtaking driver to get around him, not force him into a situation where he has to jump out of the way to avoid contact.
Anyone can brake too late and show their nose up the inside, that requires very little skill. It's cheap and nasty and I would even go as far as to say cowardly. It shows a complete lack of respect for the driver in front, akin to using the car as a tool to 'battering ram' past. Some drivers, quite rightly in my view, have decided over the years that they're not willing to put up with it, and as a result the others don't 'try it on' with them subsequently.
Driving standards became far too lax in the 1990s and perhaps the early 2000s, and without mentioning any names, several drivers got away with a lot of unreasonable behaviour. It's interesting that penalties are being issued now by stewards who were drivers, for the most part, in the years prior to that period. If this heralds a return to higher standards being expected of drivers, then I welcome it. Why? Because (1) it's unsafe, (2) it's unfair, and (3) most importantly, it sets a bad example to young racing drivers, who do not have the benefit of carbon honeycomb monocoques and impact absorption structures.