Hi,

I'm trying to modernise the exterior facade of a mid-90s 3 storey house (pitched roof) with the typical orange wavy clay tiles. I want to switch to gray flat tiles and remove the roof eaves at the top of 1st and 2nd floors to achieve a cleaner look. Research on the internet tends to indicate that the roof eaves prevent erosion/staining from rain. However, I noticed that most of the newer houses do not have roof eaves anymore so are they really necessary? So would like to invite comments and feedback on this.

Depending on where the eaves are located, they can serve another purpose. My house is designed with eaves above all the windows and this serve to prevent rain from splashing into the room to a certain extent. 
i also have eaves on the main roof as well to direct rain water away from the side wall. 
 

do note that staining usually occurs and starts from the top. If you think you can live with the staining, then can just remove them. 

maybe you can just take photos of your house first and photoshop away the existing eaves and see if you like the new look.