If the light is bright enough to light up the tank for enjoyable viewing it is plenty bright enough to grow all but the most demanding plants. And I have grown them in substrates of consistency from fine sand to ecocomplete-style to quarter inch gravel, no worries. Watch the AC Marketplace until somebody is having a sell-off-the-clippings sale and dive in. Stem plants are probably easiest but leaf- bunches like Amazon swords likewise do well in moderate lighting and about any material deep enough to hold the roots in place.
Plants can have downsides, depending in large part on where you get them (applies both to stores and private sellers here): they can bring in algae and, most especially, pest snails. Best bet with sellers here is ask upfront if they have pond or ramshorns or malaysian trumpet snails in their tanks, and if so, avoid them. Snail eggs are incredibly sturdy and even if they are cleaned of all adults you will almost certainly get an outbreak. Also plants can make vacuuming around them difficult. But there is no question, in my mind anyway, that shrimp do better in tanks with plants than in those without, for reasons cited above.
