If RequiredAddons is not planned, how do you intend server owners to make sure the required mods are loaded for players? If a player loads unallowed mods he will be kicked because of verifySignatures, so that is covered, however, what if I join the server and do not have 2 out of 10 mods loaded.
This could be used to exploit game mechanics by not having certain objects visible in-game, or not being forced to react on certain RPC's sent from the server.

All the mods will have to be loaded, similar to what EqualModRequired does now

Also not ideal, as historically people did make "optional" mods

True, for owners of private servers, there should be different options that provide the ability to specify both strictly required modifications to connect to their server (breaking this list is an exception from the server, an integrity violation or a mismatch is an exception, as is done in equalmodrequired now). Also, there must be an option that indicates modifications that are not required to connect the player on the side of his game client, but can be connected on the server side of the game (this is extremely convenient for people who make minor changes to the server side of the game in their own mind).
Yes, in the current form sigtarurechek performs its function, but not as we would like, and it does not provide decent protection. And connection equalmodrequired forces even purely server modifications to distribute for the client of a game that automatically leads both to distribution of individual developments on the server, and to superfluous problems in the form of the excess mods which are not necessary for players.
In addition to the above, there is also another problem. People entering from the game browser inside the game on the server with modifications simply kick with them, and rarely one of them can understand at least why. There is no way to indicate even the server page to such people, let alone to indicate to the player why he is excluded and what is wrong with his side. As a rule, such people simply go to look for other servers, thus online on servers that can be made interesting and unique, simply lost, and the server is forced to close.

There is a difference between optional mods and server only mods. The latter would be a mod running only on the server while the former would be a mod that client may or may not use while connecting to the server. Optional mods are not planned currently (the way it worked in arma had its own issues)

Optional mods such as sound changes or texture changes should be possible though by just adding the key to the server key folder. A player could then connect and be allowed onto the server because the key is recognized. Even if not, if the server also loads the mod it would not hurt anything either, because the server does not care about textures, or sounds or anything like that. Clientside optional mods with custom logic are not a thing really anyway since most gameplay elements require the server for providing data anyway.

Adding only the key to server wont work anymore with the new verification

I have split these into two tasks, the server browser mod part is now here https://feedback.bistudio.com/T140571

Can't you program something like equalmodsrequired? So we want to run administrative mods on our servers, (because not evenyou programed the server with a useful administrative tool where we can teleport, delete items and spawn item, since we administrators are always working out this kind of BUG on dayz) and not we can run administrative tools on our server because the client also has to need the administrative mod installed. This is ridiculous, where's your logic?

Why don't you program an official server administration tool similar to "Community Online Tools", or program some configuration similar to equalmodsrequired? This would solve the problem of verifysignatures and server security.

+1 ^^ We want to administer the server live whilst players do not need the admin tool set.. this needs to be made available.