It is disappointing to see 'Yugadi' being spelt as 'Ugadi' in majority of English print and electronic media. Not only advertisements but also headlines spell it as 'Ugadi' with elan.
The word Yugadi is made of two Sanskrit words 'Yuga' meaning year and 'Adi' meaning beginning (yugasya adi = yugadi, beginning of the year). In Roman script the former word is always written as 'Yuga' not 'Uga'. If it is so then why would one write the word in question as Ugadi when it is an extension of Yuga?
If one still insists on sticking with 'Ugadi' then 'Yoga' will be 'Oga', or 'Yahoo' should be 'Ahoo' or better still 'You' should be 'Ou'.
In a similar situation about a name being written wrongly in Kannada, I told a former editor of a widely read Kannada newspaper about it. A few days later, after consulting a couple of linguists, he told that the popular usage is alright even if it is lexicologically wrong. I was flummoxed. It is the case of a lie turning into truth when told over and over again.
Now, do 'ou' want to correct the mistake or commit it time and again until it becomes the norm? As the Kannada saying goes, raayara kudure katte aagutta? Will the king's horse turn into a donkey? 'Ou' decide.