Importance of photos in web design
Today website images can be large and have really decent quality and still load fast. So there’s really no excuse not to use photographs that can enhance the message you want to pass on to your audience through your website.
Research using eye tracking while test persons where browsing pages provides interesting results. Images are significantly contributing when they are carrying relevant information, have a meaning in the context, features real people as opposed to stock photos and are personal.  Photographs can help draw attention to content on a website, enhance information in text and make heavy text easier to digest. In fact some research shows a relation between bigger photographs the better sales numbers. 
Photos with sole purpose to fill out a page or make the page nicer looking however proved to be completely ignored by users.
Through my years as internet user seen that the quality of a website’s content, such as photos, many times are indicative of the quality of the company’s products or services. Probably it is because successful people invest in smart solutions and choose their web content accordingly.
Be fare to what you want to promote through your website and always use high quality and relevant photographs where they communicate best in the context. Use a professional photographer or spend the time needed to find that perfect photography if you use a stock photo service such as DeviantArt.