Buyan and Karakut used as antisubmarine ships? Not very likely as they have no dedicated antisubmarine equipment
They have sigma battle management system. Other plateforms will provide targeting data. They bring firepower.
Everything can be destroyed but ships are well protected against air attacks and water can't be destroyed, they don't need runways. And during crisis no one let ships at port.
Buyan are older than 22160. They stoped producing them because they have new designs. Karakurt being one of those is suppose to go farther into ocean and could follow a gorshkoc to bring 8 missiles per ship to launch massive salvos.
A simple exemple of what ships can do and not planes would be Syria. They don't need 10 kirov to protect syria. One slava to bring big radars, helicopters and big missiles and lot of smaller boats to bring fire power. Data about location of enemy ships will always be send to all ships while slava's air defence protect the whole group. They can stay there for months.
Air force would need hundreds of ships for that role and at they end they would all be so used that they would need to replace them. Planes are good when the hostilities starts and you know where to send them. But making surveillane 24/7 with planes for months is impossible.
Many wrong things you have wrote in this post.
Everything can be destroyed, even big and well defend ships, that happened many time in history, same as many ships were destroyed in ports or other hideouts during war time.
Buyan are still in production last 2 were started this year.
And if you see Buyan and Karakut just as missile transport ships then you are wrong they are more then that. But they are not wonderweapon (as seems many members of this forum see them), and they are not ASW assets, they have many limitations and they cannot replace frigates or destroyers in no task.
Surveillance with aircrafts is much more suitable then with ships as they see much further. Did you check link that Gunship posted? Ships cannot see more then 30-50 km. Aircrafts can-they can see ships up tu 400-500 km away, so one plane can do job of many ships. You really believe that Japan and USA have that big number of patrol aircrafts for no reasons? They do not lack big ships but patrol aircrafts are much needed.
Offcourse you would need decent number of aircrafts and that is just one of things that Russia lack and that Russia have to improve. Russia need new marine patrol aircrafts and need dozens of them.
Any way Russia need also big ships like Gorshov and Grigorevich and yoo cannot compensate their slow production with Buyan and Karakut, unless you find that only job for RuNy is to be costal defence force. And i hope that that will not be case.