#StartRant
The ti-83 plus / ti-84 plus se is petty old (in comparison to nspire and smartphones etc.) It is actually somewhat surprizing just how long it has lasted.  (  The main reason the calculator is still in use is because teachers, friends, relatives, etc.  all know how to use the interface.  Thus, why migrate to a new one like nsipre?  Schools which have invested heavily into the ti-83 plus series will be much more hesitant.  While the nspire's menu system is far more user friendly, the nspire (or any other calc) can hardly complete with the support for the ti-83 series.  You can find a tutorial for probably every feature of the ti-83 series but the same is not for other calcs.  If TI changed the ti-83 series sigificantly many tutorials would become useless thus making ease of use worse.  In other words any update will probably add more functions (not anything like a CAS) and fix bugs.
#EndRant

But of course this is still a great calculator and I like it a lot (it has taught me a lot about programing and pointers with axe parser.  )

There are also a lot of students who still buy the 83+/84+ mainly because of the lower price+amount of games combo. You still see some young teens in hi school being astonished when they see older students/friends/brothers playing games on a calculator, even if it's a monochrome one.

What would string do that Sub(), Instring() and Str1 to Str0 cannot?

I wonder how the syntax would look like?

And what would it display? I am kinda curious how this syntax and regular str/sub/instring syntax would compare. I never used a string() command before on any calc.

Oh ok you mean it's like a var->str command?

Sorry, I give up. I just don't understand. I sadly never used anything other than TI-83+ BASIC and am still very new to HP Prime PPL so I would probably need to learn TI-89 BASIC in order to understand, especially that I only learn with concrete examples.