in e-commerce, SEO or search engine marketing, what would be several good answers to the question “Why are you interested in working in this field?”
I don’t want to simply say “because it’s a growing industry” or “I’m looking to broaden my skills as a web developer” because that sounds like I’m mentioning the reasons for myself and not for the employer.
Thanks for your suggestions
Just waffling here, but …
“I love the challenge of helping people to maximize their online sales, and optimizing sites for search engines is a crucial part of this. I’ve researched extensively, I enjoy keeping up to date with the latest, best-practice SEO techniques, and I feel I have a lot of energy and expertise to bring to your company …”
And so on. 
There’s nothing wrong with being self serving… in fact, it can be a lot more effective than trying to say what someone wants to hear; it’s all in the spin.
For example…
A1: I am so excited to be able to use all of the expertise I have gained working in the web and learn from you to do an even better job!!!
A2: Having worked in development for xyz years, I’ve been exposed to the marketing & acquisition side of the industry but have not had the opportunity to fully explore it and I believe that it will provide a good opportunity for me in the future by allowing me to merge up my technical expertise.
A1 is fluff and says nothing… even worse it starts to infer skills you may not have. A2 is still pretty much hot air but you’re giving two important messages in that you want the job [critical to hire someone who wants to be there] and that you are looking to leverage your experience to do it [that’s your value].
No one takes a job for the employer’s sake, it’s a mutual exchange and you can give and get at the same time.
It really is all in how you word it, but be honest as well. “As a life long learner, I am interested in a field that I can help grow while I continue to grow with it.” Highlight your strengths but don’t make it seem like you are already an expert and can sit back and just coast on your current knowledge. It can be tricky, hiring managers are going to infer what they will, and ultimately if you have a good personality and are qualified, I tend to think it matters little what you say.
Thank you for your insight guys!