But, the existence of this page shows that you are forcing people to search for how to fix this error. Just saying, RTFM is the kind of attitude that hinders good UX.
For 99+% of ordinary people, âwhen I take a paint and a brush, and paint over any grid, I cover the gridâ. No, your âitâs bizarreâ, âitâs counter-intuitiveâ, âitâs opposite to what one would expectâ is not universal - it just reflects your own acquired knowledge, which you donât appreciate; every bit of âintuitivenessâ is based on your prior experience, and in not something you got with motherâs milk. And further, your position reflects your idea of âwhat is natural to me, natural to mostâ bias - hence your âI found other settings not so bizarre, but this was difficult to me - it needs the dialog!!!11â.
I repeat: EVERY SINGLE SETTING in LibreOffice will find its âwe need a dialog for that!â proponent. And no, this one isnât particularly âbizarreâ.
But, the grid is a guide, it is not formatting. Why are you erasing the guide by default, when formatting the colour of the cells?
It is irrational to show the grid for empty cells, but not for coloured cells.
Because as soon as you start painting, you explicitly define the look of your spreadsheet. The spreadsheet doesnât have a âdesign viewâ and âresult viewâ, which could differ by âdesign view shows guides, but result view doesnâtâ - so that the author would use design view, and the recipients would use result view ⌠No, there is no such difference. You are working and seeing it, as it will be in the result. Thatâs the simpler way to do it. Itâs natural (in its own way!), and is adopted by 100% of industry.
And the other alternative would be âthere is ~no way to cover part of the sheet, and make it not have a grid on screenâ (well, one would need to invent much more complex ways to do that - e.g., coloring the grid ⌠which is much more cumbersome to most).
Note by the way, that âitâs a guideâ idea itself isnât natural for most basic users. They will often get confused, when they try to print, and do not see the grid on the printout (many questions like that here on Ask) - so how do you expect them to find your idea of âgrid is not covered by background color by defaultâ ânaturalâ?
Now more to the spreadsheet specifics. Spreadsheets are, by design, tools for managing tabular data. Their idea is to provide you an area with cells. It doesnât enforce borders (because it doesnât know what size do you need, or maybe several âtablesâ on that areaâŚ), showing you a non-printing grid by default; but it is natural, that when you created a background, you will also add borders. Otherwise - how will you print your tabular data? how will you export it to PDF?
And no, the ânot everyone does thatâ argument doesnât change the most basic, intended, and natural use case. And for more esoteric ways to use the software, you canât argue that everyone needs that dialog 
The guide is there so we can distinguish the cells. When you colour the cells, then by default, you end up with an amorphous block. If that is what is wanted, then that raises the question, why bother to show a grid at all?
To provide you the initial orientation. Thatâs already enough reason, even if we ignore the âdonât use background at allâ use case.
This is completely illogical. Either you show the grid for all cells, or for none, unless a user opts to hide the grid only for filled cells.
This is completely ungrounded. Declaring either-or as the only possibilities is logically wrong here.
Enough for me. You have been given enough information at least to see that there is more than one point of view, and that the opposite point of view has its reasons. You may invent more argumentsâŚ
1 Like
You are confusing a âguideâ (the grid) with cell formatting. They are orthogonal, so why is one affecting the other, here? Itâs illogical.
Both affect what people see. And people want to see what they want, and they donât care what you call that. People who, like you, draw a line between these things, are the minority.
And no, I donât confuse them, but I clearly see how you try to put labels.
My point sailed over your head. That they both affect what we see is trivially true, but, in this case, one should not be (visually) blotting out the other.
Last time: people want to be able to paint and see a homogenous yellow surface. Your idea will require them to also apply border color (also yellow) to get what they want. That is very inconvenient to most. On the other hand, the existing situation doesnât need that.
And if people need borders over the background, the normal black borders will fit OK.
Bye.
They only need to choose the configuration option, to hide the grid for background colouring. (As I mentioned in previous comments. The default hides the grid, which is illogical, unexpected behaviour).