They are beautiful Victorian era revolvers that really are examples of a time when firearms were pieces of art, were hand fitted and Sam Colt ensured each one had a roll engraved cylinder, even during "wartime production " so you knew it was a real Colt. They were also designed to be perfectly balanced, to blow the fouling out the open top rather than back into the gun, they were simple with few moving parts , and they were tough, reliable guns that were used hard .
The Remington is an example of a simple, no frills revolver made with Industrial Revolution technology, designed to be made quickly and for less $$ to compete with Colt.
The Model P had a solid frame because that's what the US Govt wanted, the Colt 1872 open tops did not generate interest from Govt contracts. Even today, gun makers give the Govt what it specifies to win the lucrative contract. Glock was prepared to add an external safety to satisfy the US Govt contract which goes against the whole design but money is money