My client requests that we keep the landing page as the homepage because someone searching for one of our services might also be interested in the similar services that we show on our homepage and it provides a warmer welcome for our brand. What opinions do you have about this? Does AdWords still penalize you for this? In my view, it does make sense to keep the homepage as the landing page.
I think you can keep your home page as landing page, also would like to suggest to keep clear contact form of information on the home page to make more conversion.
A landing page should be a custom made page specifically targeting the users of its traffic source. I think you're missing the point of what a home page is there for.
This is where you have to educate your client about doing things the right way versus doing them the wrong way. Make custom ones per adgroup and you'll make more money for them, put it in terms they understand.