Interface interference

Somebody designs a handy web page with handy buttons here and there which can be clicked on to produce handy results.  I learn to use it and I am delighted.  What a fine product that company produces!

Then Smarty in the back office does a study.  Is the color of the page improveable?  Do fewer errors occur when the diddling-do switch button is moved to the other side?  Can we fit more helpful buttons up in that corner if we make all the buttons half size?  Results of the study come in and they imply that a few changes to the design of the page will result in faster production of the product and 20% more adoptions.

Result: Smarty gets a bonus but I get frustrations and more errors.  I had enough errors before but now I get more.

Note to Smarty,

Hands off the interface!