Three Trends to Follow:

Bigger Product Images - This allows for more detail visibility

More Robust Reviews - Offering additional information about the reviewer or better summarizing reviews makes it easier for Users to get the full benefit

Coupons You Can Use - Make it easy for Users to apply discounts or even automatically receive them 

Three Trends to Avoid:

Smaller Hidden Product Descriptions - Descriptions seem to be disappearing and this is no good, descriptions can answer questions, offer use, care, benefits, or measurement information that is important to Users

Adding Items To The Cart - Many sites fail to give adequate feedback, avoid too subtle changes on the page and be obvious that an item has been added

Cluttered Customer Service - Don't neglect the Customer Service section of your site, User don't want to see cluttered or cramped information, things need to be clear and accessible 

Being a designer is as much a consultative role as a practical one; to justify our design decisions, we need to explain to clients our guiding principles and teach them the basics of good user experience. Otherwise, we’re nothing more than pixel-pushers.

I have been seeing more websites go to the single image approach and found a few articles discussing this trend. A website study found that out of 3 million home page visits only about 1% clicked a carousel slide.

I think this can go both ways depending on the specific website and the content that is being pushed. One reason I came across made sense to me:

The navigation arrows on a most commonly used carousel don’t give users an incentive to click. These can fail to work because they don't describe the information Users get if they click it and end up ignoring it and putting their attention on something else. Labels are a better use and more informative, meaningful to Users. Labeling each slide incentivizes Users to click.

Additional arguments brought up the focus on Prioritizing content. Rather than 4-5 content pieces that get buried in the same region, choosing the most important message and display that. 

Some alternatives suggested would be to use Context-aware image sizing to "deliver optimized, contextual image sizes for responsive layouts that utilize dramatically different image sizes at different resolutions"

Interchange is an example of this, it allows you to dynamically load content on a responsive site based on user's browsers, so you can target small, medium and large images for the right use-cases.

One counterargument was: Treehouse published an article on Creating Responsive Websites with Photo Backgrounds, looking at a few different responsive techniques including how to adapt large background images to an interface:

The trend of large photographic backgrounds has become very popular in recent years. The improvement of Internet connections has allowed more data transfer per second, which means images can load a lot quicker in real-time. There are also plenty of open source scripts out there for generating cross-browser support using fixed photo backgrounds.

In the end, I think the decision comes down to the content and what you're providing through an image. I would like to look into this more but found these articles helped me think about what I want to say with images or carousels in a different way. I would love to know what other people think of this as well.