Rajat,
There is a context to the high pressure rounds problem though today's obsession with monster bores is madness in my opinion. That said, if someone wants to spend their hard earned money on something phenomenally powerful, it's their money, I guess...
After WW-2 when Indian orders began to dry up and several British gunmakers were struggling, they had no option but to look for markets in other parts of the world. The USA was the first big market that they found and they had to offer their rifles for rounds available there. Kynoch's going out of business also meant that there was no real source for ammunition for many of the old double rifles. Winchester came out with their 458 magnum, a round designed to fit in a 30-06 length action and they wanted to make it perform like the 450 No 2 with a 500 grain bullet leaving the barrel at 2150 fps. To get this performance they had to load it to very high pressures. AT this time, Roy Weatherby, an insurance salesman who became a marketing genius extraordinaire decided to make the world's most powerful round, with his 460 Weatherby which fired the same 500 grain bullet at 2700 fps. He had to sell it with a muzzle break, though, because it was capable of seriously injuring the shooter without one. Then came the whole madness of ever more powerful rounds - the 475 A&M Magnum based on the 460 Weatherby case and the later 585 Nyati, 577 T-Rex and other monster bores.
There is some sanity these days, though - Weatherby load their 460 down to 2600 fps and the fact is that the big bore guns that are made usually are on the market second hand with very few rounds fired.

The old standard 404 Jeffery is more popular than ever in bolt action rifles and in doubles the superb 450-400 has been brought back. I do think that many have seen the light after being blinded by the smack of a monster gun in full recoil.
As far as Marcel Thys' efforts were concerned, he was the head of a school of sporting arms design and is one of the greatest gun designers alive today, though he has sadly retired and closed his firm down. His sons did not take the business up after him. Thys took up the challenge of building double rifles in the very high pressure rounds to show that he could do it and still have a double rifle which was the same in profile as the guns of old and which handled as well. It was a design challenge which he took up and I would say hat's off to him for his work. Other designers like Claude Bouchet have also designed their own rifles but the average Bouchet rifle looks like a huge cannon and probably weighs as much as 15 Kg or more. His work is not a patch on Thys'. Others like Harald Wolf have also made these guns though Wolf only makes his trademark 500 Jeffery rifles these days.
Mehul