The quick answer is yes it's done on purpose.
The long answer:
Tekken is not best played by dialing the combos, you can do it, but your going to just be a mediocre player at best.
Tekken is best played with out spacing (better position) your opponent, making them whiff so you can punish their bad spacing choice. Poking your opponent (Street fighter calls these footsies). And using that poking to set-up your launchers, and or use poking for better spacing or guard advantages.
I just find it doesn't feel like even the Tekken I'm used to. It feels more like Injustice, in that I'm not deciding to continue along with the 2 or 3 parts after a confirm with a string due to seeing it hit, and wanting to move on with it. I'm needing to do the particular string fully, let it's animations play out, and then move again.
I guess it's because of Tekken's newer juggles since 2 and 5. It's making it feel clunky, because I'm not getting to confirm the blow and then press the rest, I'm having to dial the whole thing in before I even see if I timed the first hits right.
As I said you can dial a combo...
But then you're not maximizing your effectiveness. As some combos you should only do the first part, so you can cancel the next part into a different move or into another different Combo. It all depends how quick the recovery is in the combo for you to mix and match and be creative to play the way you want to play.
Some of the faster recovery Combos are ment for poking. And you'll know what is fast recovery versus slow recovery just by doing the combo. And stop in the middle of a combo, the ones that recover fast in the middle, are the one's to use for poking and mixing things up. For the juggles thats when the dial-a-combo really comes into effect. The purpose is as the Director Harada says (I'm paraphrasing here: "In our test when a player does a juggle their enjoyment of the game is at it's peak, so we want to have juggles that are accessible to all players")
Most of the slow recovery combos are more designed for juggles. So these combos are ment to be easy, for player enjoyment, however if you just doing the combo without thinking about how the opponent lands, where they land, are they face up when they land or face down etc. then your missing the important nuance and the higher levels of play in the juggle system.
Or juggles where you could try and do that maximum damage, but decide instead to do an easy juggle because you know you can land the easier juggle 99% of the time as opposed to the harder juggle 70% of the time.
Or juggles that purposely stop early landing the opponent at your feet, so now the opponent has to decide how to get up, and if they get up wrong you get another juggle this time for even more damage.
For the fast recovery combos that recover in the middle of the combo, use those as pokes. And explore such as "Brocken Rhythm" that is making combos Rhythum slower or stopped completely to go into a different string-of-combos. This Brocken Rhythum makes opponents want to interrupt, but its a risk for them to do it. (And a risk for you too, but a reward for who ever executes better, better reflexes, or set-ups you have developed, and who plays the better mind games etc.)
See. that's the thing. I love breaking / adjusting Rhythm in VF5-ish combos, because the buttons have enough of a delay built in either from holds or the final blow, of even in mid-combo. It feels organic, because I can do this with almost any combo, and make the change around the point of impact.
Right now in Tekken, it feels like there's, say, 3 combos per character that allow this. But the rest are pre-programed full strings that only let me do the combo 1 way. Josie has a few feint combos where she can delay the final blow, and that's cool. But I wish I could do this more freely. It just feels odd here, because I swear earlier Tekken games,,, Soul Calibur series... and VF, didn't feel this stiff, in that regard.
That, or Virtua Fighter 5 FS is so loose with it, that I expect Tekken to do the same. It's one or the other!
You're suggesting that Tekken's way of modifying strings is not by timing the presses within the strings differently (my preference), but stopping them early entirely, at different points. This feels kinda limiting to me, but at the same time, I can see it being easier to digest for some players than the alternative.
I know the answer is a bit long and I could add a little more information, but I hope this answers your question.
Yeah, it's appreciated! I'm a lapsed fan of Tekken, and I never liked the ugly movement shuffle many players do in it, lol. So whenever I come back to it, even though a LOT of it looks and controls the same, the changes in the underlying core always feel off.
Just more reason for Eliza to force me to stick with her, lol. Her "1,1" literally being a pair of special move-cancellable POKES just works, and makes sense.