Then perhaps you were lucky, as my experience is vice-versa, and I have installed lots of graphics cards. Personally, in my own PCs I have used a Rage 128 Pro, a Radeon 9000, a Radeon 9200, and now a Radeon X1600, and never had any problems except the Alt+Tab thing which I can easily tolerate.
But you can also derive it from history: In the old 486 times, ATI was not known to be a high-performance graphics card manufacturer at all. Yet they already had by far the greatest market share, because they had their cards in most office PCs. Back then, gamers rather went for S3 for fast 2D cards, and later for 3Dfx when the age of 3D acceleration began. Totally dominating the 3D market, 3Dfx neglected to keep up their research and found themselves suddenly outclassed by the newcomer nVidia, who introduced their first good 3D card with the Riva 128 and took over in performance leadership with the first GeForce cards. 3Dfx went bankrupt, but ATI, who had dominated the office-PC market all the time, finally decided to enter the branch of 3D performance competition with their new Radeon chipset. Since then these two companies battle it out against each other, but ATI still has its professional background, knowing that their business customers expect solid video signals and stable drivers, while nVidia, who always had the gaming background, are more experimental in their approaches and sloppier in signal and driver quality.
ESO is a good example for the difference between professional and gamer service. Do you think any software manufacturer could survive by offering such a crappy patch and server support as ES does for AoM? No company would keep using such software. However, gamers are more tolerant to suffering and being treated like crap, which is why they are treated that way.
Darkness is a state of mind
Valor is the contempt of Death and Pain. (Tacitus)
Problems worthy of attack prove their worth by hitting back. (Piet Hein)