With the innovations in racquet and string technology, tennis has become much more power oriented.
Most players try to use the speed of the shot as their primary weapon to win the point. Players try to hit the ball "through" their opponents or get it back to them with enough speed to force an error.
The drop shot and the lob can still be used very effectively to complement the power game. Hitting the ball short and soft after a hard, deep, and powerful shot can be very effective since the opponent will likely be on their back foot. Also, if the opponent is at the net or you are able to draw them into the net with a drop shot, the lob becomes a great way to expand the court and make your opponent cover a larger area. The longer the opponent is at the net, the easier it will be to get a lob over their head.
In doubles it is often effective to use the lob after a player has closed in. Your lob will not have to be as good (deep) and it will keep players from closing in as quickly, making their volleys more difficult.
Don't forget to use these two shots to keep your opponent off balance and make them move!