I thought I'd create a thread focusing on any missed opportunities by the producers and writing team in regards to characterisation and storylines. Examples of when it looks like the producers have thought of a way of developing characters and new plots only for them to hit a dead end:

Roxy and Alfie's friendship: Back in 2011, they had a really refreshing bond which seemed to have been ruined by them inevitably getting together before Alfie inevitably dumping Roxy for Kat. They should have just remained friends.

Whitney, Stacey & Lily: It's only now that Whitney and Stacey have had quite a bit of screen time together but if it is true that Whitney is leaving, then this nice development is too late.

Aleks and Alfie's feud.

When Aleks said (about Alfie) 'he may have won this battle but he hasn't won the war' (or words to that effect) it seemed as though there was more to come but...

Nothing!

The Slater/Moon house fire should have been started by a mystery person which would later turn out to be Aleks, (his motive would have been revenge on Alfie for poking his nose into his business and interfering in his relationship with Roxy) but Kat gets burnt instead of Alfie, who saves her.

Also Alfie and Mick's friendship.

I would of liked to of seen some storyline/interaction between Janine and Tanya.

Always thought that Pauline should have visited Wicked Willy in her final months to enact a horrible revenge for what he did to Arthur

Shirley should have had the Vic after Peggy left

Mrs Patel should have been a semi regular character

Emma Summerhayes was a great and refreshing character, think they should have kept her on

similar to the OP about Alfie/Roxy, I think that Mandy Salter would have worked better on the show as a close friend to Ian rather than his reluctant fiancé. She was a breath of fresh air for the Beale house when she first came back but it was downhill from there. And she didn't really have a whole lot to do with Pat (a character who's exit storyline has caused a whole lot of missed opportunities) either which is a shame as it would have been a throwback to the past. And she could have been used better as a close friend for Roxy during Ronnie's abscence

Mandy being Lola's mum.

It would've been a fantastic storyline - everyone was convinced it was going to happen, but sadly it wasn't to be. Both characters would've hugely benefitted and developed from it. Instead, Mandy was paired up with Ian for a few months and then axed, and Lola has been severely underused throughout her four years on the show

Den never going toe to toe with Grant or slinging Peggy out of his pub!!!

~ Not making Cindy Williams Jnr. Lucy's Killer.

~ Denise's alcohol dependency not being explored.

~ Not using Jamie Borthwick's acting talents.

~ Not integrating Mo Harris into the Stacey/Martin/Lily unit.

~ Not exploring the Ben/Lola/Lexi dynamic and getting rid of Lola and Lexi just before Kathy returned.

Killing Pat

Not killing Peggy of in the Vic fire.

Not making her Archie's murderer.

Not leaving Paul Truman alive.

Both the Banshee and the Philth should have burned to death in the fire he started (nearly killing Stace and Lily in the process).

Definitely this. You could just imagine Paul back on the square and I'm sure there would be some banter between him and Vincent. He could also get together with Denise.

Charlie Cotton. So much potential, links with Dot, relationship with Ronnie. All ruined by his affair with Roxy and inevitable departure after Ronnie's relationship with Vincent is revealed.

Clare Bates. Another character with links to the long running characters. Turned her into a clone of Clare Devine from Hollyoaks, just without the red outfits.

BIB Hideous character one of the worst ever, shame the actress has none of the talent of her brother

Having Carol make a call to David just before she left the sqaure

I love Stacey and Whitney together, makes so much better sense than Stacey suddenly being Shabnam's best mate. I think Whitney is horribly underused.

Dean and Mick being explored as brothers as opposed to Dean/Linda.
Denise's alcoholism storyline being dropped.

Den Watts being killed off
Mick and Dean as friendly brothers rather than enemies - Dean should never have been Linda's rapist.
Charlie Cotton's profession, he should have been a high flyer and mysterious and had much more depth
Denise not being Lucy's killer
Not letting Kathy meet Lola

Denise's neglect of Patrick, and her potential alcoholism storyline seemed to go nowhere which was a shame - I always think scenes involving her are going to lead somewhere, but they never do.

What a brilliant post...

Talking about Mo, where is she? Has the actress been axed?

I just realised you are praising your own post A certain brilliance in that!

Did... did... I just agree with you, Aar?! This isn't right at all... I would recommend throwing in an "absolutely despise", or perhaps a "loathe her" into the post, but other than that, I can't fault it.

Anything involving Denise and Jay (or rather the lack of and the fact that they seem to always get dropped half finished).

Linda's rape- Should have focused more on Linda and the effect it had on her (like what we saw on Friday) instead of adding fuel to a Shirley/Mick/Dean feud

Getting rid of Cindy Jr who still had potential IMO

Getting rid of Lola who still had potential IMO

Spoiling Ronnie and Charlie with the dull Roxy/Charlie and Ronnie/Vincent affairs

KILLING OFF PAT!!!!!! Should have left the door open and im sure she would be back by now.

I wondered why I agreed with it so much!