Yes. You’ll find it easier to use, and your visitors (potential customers) will have a more engaging experience. Bugs & glitches appear in software all the time, so updating the plug-ins & themes helps address issues you might not even know you have!
If you want people to visit your site, stay there and hopefully buy from you – then you need to update your site regularly. It’s as simple as that. Oh, your SEO will suffer too if you don’t keep up with your website maintenance schedule.