D&D 5E Splitting your Move - The Move-Attack-Move Dynamic

The whole polearm thing doesn't seem any different from before.

In the current system you run up, poke, and run back. On his turn he runs up to you and attacks. On your next turn to continue your shenanigans you must eat an attack of opportunity as the 5-foot step doesn't seem to exist anymore.

In 3.5/Pathfinder the Polearm user would run to his maximum range, attack, and his turn would be over. The enemy has to use his movement to approach, then attack. Then he loses the rest of his movement due to move-attack-move not existing. The polearm use can 5-foot step back, but there isn't a ton of benefit since next turn the enemy will just 5-foot step towards you.

Move-attack-move seems to be nothing but good for the melee dynamics.

Ranged is a different story, move-shoot-move back into cover could be very powerful. However, its impact can also be reduced with simple rules. For example if you do not either start or end your turn with LoS to your target then ranged attacks are made at a disadvantage. It is a solvable problem if a problem emerges.

Our table was terribly used to Pathfinder and 3.5 and found 5e fluid but lacking in strategy when it came to combat.

On the one hand AoP was almost gone so people could run circles around monsters or if wanted to flee just disengage without any consequences (as long as you side stepped).

Then no flanking..

And finally people could move, act and move like crazy (or at least the full move), this lead to Casters literally staying behind a wall all combat, players (or monsters) at a door and switching with their whole gang places to train wreck poor Hodor.

Ranged attacks with the move-attack-move, as with spell casting, getting back to cover should not be much of an issue. But, moving 10 ft, loading, shooting (several times), and moving 20 ft, seems extreme.

Some of the mentioned things lead to fluid combat, some to no strategy, some to broken-ness. Plain chaos, which might be what combat should be...?

This all sounds crazy when thinking about 6 second rounds..but people can spin in in roleplay I guess.

Just our experience.