IME it would alter the game quite a bit from a Combat As War standpoint, though not necessarily for the worse.
In today's 5E ruleset, having a Sharpshooter in the party trivializes certain problems, which means you can solve certain other problems by reducing them to already-solved problems.
Example: from a Combat As War standpoint, if you've got a party that includes a Sharpshooter Eldritch Knight 8 with Expeditious Retreat and forty hobgoblins in a wooden fortification guarding a pass, what makes the hobgoblins an obstacle is the total cover they can get from the fort. If the wizard can cast Invisibility on the rogue, who sets fire to the fort and burns it down, then you don't actually have to play out in detail all of the individual hobgoblin deaths: they can't win (assuming reasonable intelligence on the part of the PCs).
So here we have something which is never directly shown in play (a fight between a Sharpshooter and 40 Hobgoblins, involving hundreds of die rolls and ending in a bunch of dead or surrendered hobs) which would nevertheless impact play if weapon ranges were reduced ("invisible thief burns down fort" would no longer be as attractive as a strategy).
Depends on how they were reduced. Right now the ranges are designed in a way that binds the gm's hands to allow a player to say they don't care about all but the most blatant of "you can't" levels of of shutdown from the gm.
If they were reduced to something like "100foot*" with the star being a footnote that sometimes the gm might deem longer ranges appropriate things change towards mutual fun for the table. That sort of footnote was suggested by someone earlier & it changes long range engagement from binding the gm to empowering the gm in ways that let them
create fun. Using your scenario of the tower the gm can choose to allow the archer to make a meaningful impact that still includes the rest of the group in
a plan that fits the toolset available to the other PCs instead of just making the gm handwave the whole scenario. With that kind of footnoted empowerment GMs even go back to creating old school problems some other player(s) would need to solve by being awesome too as part of the new scenario by declarative fiat without pushback over RAW because the whole thing is the gm using rule zero to empower everyone to be awesome.
Why not make the VTT generate the details? A good VTT should be able to accept GM input stating something like "fill in the quarter mile between the road and the farmhouse with rough terrain: wheat fields in the process of growing and occasional rocks, trees, or creeks."
Isn't the whole point of VTTs that they can be customized via plugins/etc.?
If that's not supported you can always just tell your players the above, and ask them to ask you to insert rocks and creekbeds anywhere important that they imagine them. (Any region neither you nor the players care about is fairly safe to ignore.)
To answer your question from post 180 yes there are tools like flowscape that could generate that kind of thing & it's absolutely trivial to use a randomized brush tool
Filling it manually is trivial as shown & not too tough but runs into one of two very serious problems that IME defeat the purpose in practice. It runs into those problems because the mechanics of 5e fight to ensure the collision by overextending the effective range of PCs while stripping GMs of tools once present in the past to manage those ranges.
Ultimately those problems go back into straining the social contract when it's
already taking some pressure from the GM nerfing the "
several thousand yards" of vision and players assume themselves to have in support of comically over-ranged abilities that the GM will often also need to stomp just to keep the encounter something the group can all participate in. Either the terrain is so densely packed with things that provide
total cover that you've just created the equivalent of a forest sized = hedge wall/maze to block LoS from anywhere to anywhere that very much does not belong in most places -or- it looks OK & is believable but it can almost certainly be ignored just by a PC moving to the side a bit to where there
is clear LoS to the target after asking the gm to zoom out. You can't make an entire world that looks like the
darien gap seem at all believable.
All of the people who keep saying things like "the DM should just do x" & "just tell your players Y" throughout this entire thread have been demonstrating very clearly hoe much pressure doing those things places on the social contract too. No matter
what the GM does to fix this rules issue there will be a bunch of other things that a
real GM with proper skills
should have done instead & one or two of those might knowingly or unknowingly nerf or shut down a particular player in ways that player feels nonplussed or worse about.
