So I'm going to voice the unpopular opinion of actually still liking Duck.
Before I start, I totally get why people dislike him nowadays. All he's done is put in a few great western lines here and there, be the subject of a 'duck' pun, and that's about it. But I feel that the hate is getting misdirected at the character, when it should be at how he's written.
I'd like to mention some of Duck's characteristics, and compare them to other characters in the show. The most obvious one is he's proud of his heritage and background. Whilst other characters like Donald, Douglas, or Oliver are also proud of their origins, Duck is arguably the most prideful in this regard. But he didn't always bring it up back in the day, in fact, he only said it a few times. Now, every time he's on screen, the writers have decided that he has to say the catchphrase, and have limited him from saying much else from it. They see it as some sort of running gag/line, but it's gotten old quite fast. But there are plenty of other lines used constantly in the show that for some reason, we don't find grating. Such as "Really Useful Engine", "luckily no one was hurt", "you have caused confusion and delay" etc. Also, we say Duck is so one-dimensional, but that's only one side of him, Most of the time, the other characters in the show are fairly one dimensional, James being prideful, Gordon being arrogant, Percy being naive, Edward wise etc. They all have the same building foundation as Duck does, but they've had much more time to develop traits and other things making them more fleshed out. Something Duck hasn't had the opportunity for. Moving on, this would be the first time Duck has been on screen in a long time, and they basically have to reintroduce him to a totally new audience. The writers see this as the most important aspect of his character, just how Thomas is cheeky, James is vain, etc. This is actually quite important to establish a dominant trait or feature for each character so that children can recognize them better. A character that didn't have this during his introduction was Porter. He's hard-working (almost every engine on sodor...?) and that's about it...we're not given any distinguished characteristics about him. I'm really hoping that all of this catchphrase stuff is only their 'intro' for Duck, and they drop it down to develop the other parts of his character. Like what? For one, he's extremely sassy when the situation calls for it, but he knows when to joke and when to stand firm. He'll act on his instincts, even if they may not be correct. He can't let himself not act, and he won't panic. I think the closest character to this would be James, but he doesn't usually have the wisdom factor playing, thus most of his actions are rather ignorant and don't end well. Duck is totally self assured, and can be seen as being haughty, but he only thinks he's in the right, which loops right back into his pride of his heritage, with the Great Western way being the right way. There is much more to his character than meets the eye, and I'm really going on shadows of things he's said and done throughout the years. But I feel that the 'hate' for this character is totally uncalled for, and instead the way he's written in the series is to blame.
Sorry if I've offended anyone, this is only my opinion. You don't have to agree with it, but I ask you respect it.