I know a lot of players both new and old don't like them, but as a DM, I like random encounters. They add an element of realism to a game. - the unexpected and unplanned for. I've read in various places that some folks bemoan any sort of randomness in encounters because they introduce the potential for unbalancing a game. Well, sometimes in life, shit happens. Deal with it – the option to run away or hide from an unbalanced encounter may not seem heroic to some, but I submit to you that heroic hardly means stupid.
I live in a rural area. Walks in the woods are fairly common around here – Hell, in every direction I look in town, I see trees, so one could argue that our town is situated in the woods. You just can't plan what you're going to see or run into when you step into the wilds. Might be squirrels, might be rabbits, might be deer, could be a bear – there have been bear sightings in this area as close to civilization as our local park. Just a few days ago, fellow Outlaw D&D contributor and member, DM Brett Swigert, ran into a Bard Owl in fairly close proximity to himself. Naturally he took pictures but did not approach the huge bird.
Not all Random Encounters need be a fight. The 5E DMG literally defines this concept, which I have no problem with. What I have issues with is everything being so darned balanced. If I walk into my woods, I could very well run into a bear, and that's pretty unbalanced and unfair, but I am in no way obligated to fight the bear. Remember, the distance of the encountered (See older editions – they still have much to contribute to a 5E gaming experience) … it may not be right on top of you .. it could be far away enough to avoid.
The frequency of encounters – 18+ on a D20 - seemed pretty rare to me at first until I did the math (ugh) … that's a 15% chance compared to the 16.6% chance on a 1-6 from the old school. That's not too bad. But I wonder if the upcoming Tomb of Annihilation, based in the Jungles of Chult, will alter the method of rolling for random encounters. I think it should, to reflect the enormous amount of life – and undead - scurrying around in the place. 1 on a D4 seems about right in such an untamed environment to me, but time will tell on that.
For those of us who run hexcrawls, like I am in our current Chult Expedition – no, we couldn't wait for Tomb of Annihilation to get a Jungle Adventure going – The lack of official Random Encounter Tables puts undue extra work on a DM. So far, this is the only place I find 5E to be lacking. I quickly fixed the problem by utilizing a chapter of Kellri's fantastic supplement for 1E, Classic Dungeon Designer's Netbook #4 - Encounters Reference, which is available through a link on our download page. It's a fine start, covering just about every terrain type out there and, of course, begs to be customized by clever Dms as well.
Anyways, I've tossed my two coppers into the pot. I hope my ramblings might help someone, but as always, YMMV.