My way of thinking about it is... if Microsoft is/has dropped support for IE8 and lower so have I .... if I was worried about that I might as well build all my sites with Netscape in mind too then... maybe charge my clients a few hundred more for all the time it would take to fix it. Even then it would be incredibly hard to do.

Any potential customer that would be using xp or lower will be having the same issues with 99% of the sites they visit. I always remind my clients to focus on what is more important... the 5-15% of people using outdated browsers or the 85-95% that are not. My numbers my be leaning a bit one way but from what research I have done I will cater to the bigger number.

It is a big security risk and a inferior experience being on the web with IE 8/9/10.. The word inferior is important here, it does not mean the design looks totally broken on these browsers. As an example, when using flexbox it might mean that elements stack instead of being displayed as a row. Generally speaking the site is still functional (links can be clicked) content is still accessible, certain things might just look a little off.

From what I know there's still people that don't have the choice or don't realize they should upgrade. The question to be asked here is, would those be your target audience / customers? Just to share our numbers, over the last 90 days each of the above mentioned old IE browsers contribute 0.2% to our total traffic. Personally I feel it is highly unlikely that these people are interested in using Responsive Web Design apps

There's just so much to think about in web design/development these days. I remember not too long ago when we were all building static non-responsive sites and all they really contained was text and images . There was no resizing of anything — it was simple.

Where do you draw the line? Do you even cater to people still using Internet Explorer 1–7? The fact is, it is more bother than it's worth.