Planned vs unplanned roadtrips- pros and cons

Till early this year, most of my roadtrips were well planned- I would decide on when we would leave from home, how far is the first destination, when can we reach there, where to stay there- book budget hotels (mostly via stayzilla), what all to visit etc. This extensive planning gave us assurance that everything is taken care of and there is less uncertainty. But they also have their own set of disadvantages. Some pros and cons of such well planned trips as below

Advantages
-    Assurance that everything is taken care of- no uncertainty on where to stay, what if rooms are not available etc
-    Helps stick to pre-defined agenda and complete the trip mostly within planned time and budget

Disadvantages
-    Compromise on flexibility- last minute change of timing/destination or delays can affect subsequent schedule. Cancellation charges can be heavy
-    Even if I find a better/cheaper hotel than one already booked, we will be forced to go to where we have the booking. In many towns though we could find better options as we enter town, we had to spend extra time finding out where is our pre-booked hotel and reaching it, even if it is a bit far.
-    Pressure on schedule to complete everything as planned

But of late, I have tried few road trips without too much planning. In November, after Bali trip got cancelled, I booked a car and hit the road, with no specific schedule or plan. We wanted to head to Rameshwaram straight, but decided to stop at Trichy. As we found a well maintained budget accommodation (Yatri Nivas) we decided to visit Tanjavore, come back, spend a night in Trichy and head to Rameshwaram next day. We reached Rameshwaram on a weekend, but still could get some decent rooms (though our preferred Hotel Tamil Nadu was sold out). We spent few more days with adhoc planning, staying at hotels in Dindigul, and a highway hotel near Erode. There was a small fear as to what to do if we all hotels are sold out. But it was not peak tourist season and such a probability was low. Also we had a backup plan to get into the car and drive to next city, so there was no worries. Before selecting the room we could physically verify that rooms are decent, at times negotiate a bit. So this mode of unplanned trip was also fun. It gave us lots of flexibility.

Another point I noted was that many super cheap budget hotels in small towns are not yet listed properly on major hotel booking portals. So if you try to book online you will usually find only few expensive options. Even when listed, sometimes they put photos of their most expensive room and put rent of least expensive room, trying to mislead. Visiting in person gets you clear idea of what's on offer and if it is worth.

I know many friends who venture out without too much of planning. I think that has an element of adventure in itself. What is your take? Would you plan everything before leaving home or would you like to enjoy a trip as it unfolds?