Budget airlines can be great. Passengers will always want to get from A to B as quickly and efficiently as possible without fuss, low cost carriers are perfect for this. Because of their network model, budget rarely have a hub. Say I want to go from Tel Aviv to Gibraltar. I hop on an easyJet - no qualms, few hours and job done. However, this is where conventional airlines fall short - because they operate a ‘hub, trunk and spoke’ model, meaning that if I get on a BA flight, I will likely have to connect from Tel Aviv to Gibraltar through Heathrow or Gatwick, likely incurring a layover timed drawing out the process. So all in all, as businesses, low cost carriers can be damaging to the running of conventional airlines, especially on low demand routes - customers almost always go for the option that is easiest.
That said, theres a reason budget airlines are nicknamed ‘no frills airlines’ - the service isn’t ‘all that’ - My father affectionately coined the term SleasyJet to describe easyJet, as everything about their service seems to be extra. despite this I think customers should know what they are booking, they shouldn’t seem so shocked when the service can often appear basic, unlike perhaps an Emirates flight where you can talk to a flight attendant about horse racing in Dubai (I have actually done this). The term ‘you get what you pay for’ is always applicable to air travel, especially with budget groups.
So to summarise and conclude, Low cost carriers are fantastic and revolutionary for the customer as travel is simplified (where do you think easyJet got their name from), moreover the business model of a budget airline is revolutionary as they all have a cost focus approach for a huge market segment. However, they are a trouble for higher cost airlines - take a look at BA, they have massively modified their short haul aircraft and the way they run the service on shorter flights, in efforts to compete with these cheaper airlines, favoured by the customer more and more.
I’ve only ever had one bad experience with budget airlines, and it kept happening over and over again. And that was Ryanair’s landings! Rough as hell, every time!