It pretty much boils down to art assets that we have available. We do not have an active artist to design new assets so the only images we can use for menu buttons is what is already available.
There are way too many clicks needed just to reach the login rewards, messages, or quests.
Any of those menus are two clicks away from any other menu other than settings (bell icon in bottom left bar). Login rewards also pop up on startup if you have a reward available, so realistically you don't even need to open it by yourself - and if you're actively checking your quests while playing, it'd mean the quests menu will open by default as the last viewed menu from that menu group. Am I missing something or is the complaint that they all need to be accessed in a single click at any given time?
Also, when you go to the 'Tools' section, there's no back button.
Tools screen does not have a back button because it's one of the main sections of the menu - same as Play or Store. Showing a separate navigation bar for Tools would actually imply more clicks to get around.