I actually share the opinion with the OP about the need for a tennis game with hybrid controls. Granted though the tuning, balance, and feel of TE is great as it is now, I can confidently attest that the addition of a keyboard + mouse (AKA "hybrid") control scheme would make for the "killer-app" of tennis simulations IMHO not only in terms of accessibility, but also gameplay and realism if done right.
I wrote up a full analysis and I'm including it as a text file because this forum's moderation setting says my full post looks "too spammy". Please let me know if you have any thoughts, comments, rebuttals, or simply want to brainstorm more about this idea!
On LinkedIn: Benjamin X Chang
[EDIT by ManuTOO: file put into the message with slight edits]
Hi all, kenBlade here. My real name is Benjamin and I'm a former Disney Interactive employee and 2K Games games user researcher and contributed to Top Spin 4 and about a dozen other AAA and indie titles.
I actually share the opinion with the OP about the need for a tennis game with hybrid controls. Granted though the tuning, balance, and feel of TE is great as it is now, I can confidently attest that the this addition of a keyboard + mouse (AKA "hybrid") control scheme would make for the "killer-app" of tennis simulations IMHO.
Rationale: We live in an age of increased accessibility in games, whether it be 1st person/3rd person shooter games and action games or AAA sports games. To appeal to a bigger audience, and especially those in real life who play tennis at the UTR 4.0+/NTRP 4.0+ level, I personally want a tennis game where we can do what the OP mentioned -- change ball directions last minute quickly, and even dangerously close to the lines or the net if needed. Reason being, this is what tennis pros do during difficult passing shots and disguised drop shots and lobs. With tennis games as a genre, my issue this doesn't feel right without a hybrid control setup. Whether simulator or arcade style.
Granted, a hybrid mouse + keyboard control scheme would have to be carefully balanced to keep other control schemes competitive. Perhaps giving hybrid users increased risk when last minute direction changes are made, or making this a special skill or stat that only some players may possess or opt into. Or simply adding matchmaking options (more on this below). As for realism, real life tennis players have to train methodically to add these types of "tricky" shots into their tennis arsenal. As a developer, I know this is easier said than done so I don't blame Manu for putting this idea in the freezer for now... but please please still keep this on the backlog

side note 1: I liken this debate to the current state of fighting games and shooter games. The keyboard + mouse combo always being better than a console gamepad in shooter games, and arcade joysticks are often better than gamepads for fighting games at the highest levels (at least for 2D fighting games). I understand that Manu does not want to create an ecosystem where players are forced to use a hybrid setup to compete at the highest levels -- however I do believe it will attract more players and bring an extra level of depth and realism to TE if he does. Another idea is if we look at racing in real life or video games, they have leagues, so one way to overcome this is allow players in matchmaking to specify that they only want to play other hybrid controls players, or to filter them out (e.g. I like keyboard controls they are now, and don't want to deal with these "unfair" players who can hit realistic passing shots and disguise drop shots/lobs in a more deadly fashion).
side note 2: Since 2018, I've tested this control setup in Unity prototypes and loved it so much that I quit being a researcher and started doing indie game development full time for about a year. Dealing with these complexities gave me so much respect for TE code! I now do full stack software engineering at a Fortune 700 firm, but still dream of making the shift back to the games space when my finances are more stable (wife and 2 kids, bills, live on US east coast now and not west coast... endless excuses). If you made it this far in my overly long post, I'd like to thank you for listening to me pour out my heart and soul on a topic I've analyzed over a decade as a tennis player, competitive game player, and game developer. I believe the gaming world is ready for a tennis game control scheme like this, and it's just a matter of having the right team of individuals to program it and balance it (again, huge shoutout to Manu for being our pioneers). And shameless plug -- I'm always available to talk games and collaborate part-time, whether it be coding or design.